WO2019222321A1 - Stiffened thin inorganic membranes and methods for making the same - Google Patents

Abstract

A stiffened thin ceramic membrane comprises a membrane layer with a ceramic composition, a thickness less than or equal to about 100 µm, and a radius greater than or equal to about 20 mm and less than or equal to about 350 mm. A perimetrical glass frit rib is bonded to a first surface of the membrane layer. The perimetrical glass frit rib comprises a thickness between about 10 µm and about 200 µm, and a width of less than or equal to about 10 mm. The perimetrical glass frit rib may be spaced from a perimeter of the membrane layer by less than or equal to about 5.0 mm. The membrane layer with the perimetrical glass frit rib bonded to the first surface comprises an out-of-plane deflection, per unit length, of less than about 0.2 µm/mm and may be utilized as an entry window for a parallel plate ionization chamber.

Description

STIFFENED THIN INORGANIC MEMBRANES AND

METHODS FOR MAKING THE SAME

Cross-Reference to Related Applications

[0001] This application claims the benefit of priority of U.S. Provisional Application Serial No. 62/672,836 filed on May 17, 2018 the contents of which are relied upon and incorporated herein by reference in their entirety as if fully set forth below.

BACKGROUND

Field

[0002] The present specification generally relates to thin inorganic membranes, and, more specifically, to stiffened thin inorganic membranes.

Technical Background

[0003] Parallel-plate ionization chambers (PPICs) comprise an entry window with a polarizing electrode and a back wall with a collecting electrode separated by a small gap of 2 millimeters (mm) or less. Example entry windows are formed from polymer membranes layers with a thickness of about 20 micrometers (pm).

SUMMARY

[0004] Medical uses of radiation, either alone or in conjunction with surgery and/or chemotherapy, use high-energy radiation such as x-rays to damage cancer cells and treat tumors in the breast, prostate, head, neck, lung and the like. Assessing the radiation dose received by an organ in the body is essential to an evaluation of the risks and benefits of any radiation procedure. An ionization chamber may be used for measuring radiation output of an irradiation device (e.g., an x-ray machine). One type of ionization chamber is a parallel- plate ionization chamber (PPIC). A PPIC is shaped like a small disc with two parallel planar walls spaced apart from each other and a gas (e.g., air) present between the two parallel planar walls. One of the planar walls serves as an entry window with a polarizing electrode and the other planar wall serves as a back wall with a collecting electrode. To maximize current output of a PPIC, a gap between the two planar walls should be less than about 2 millimeters (mm). [0005] The entry window of a PPIC is typically constructed from a metallized polymer membrane (e.g., a polyester membrane, a polyimide membrane, etc.) with a thickness of around 20 micrometers (pm). The metallized polymer membrane is bolted to a frame and the frame applies tension to the polymer membrane such that a consistent gap is maintained between the entry window and the back wall. However, radiation damage to and subsequent out-of-plane deflection of the polymer membrane typically requires replacement of the polymer membrane every two years thereby resulting in undesired service down time. Accordingly, new ionization chamber designs with entry windows with an extended service life have been of interest.

[0006] One material of interest for use as a PPIC entry window is ytrrium stabilized zirconia (YSZ). Ytrrium stabilized zirconia has excellent radiation hardening performance and can be formed into a thin membrane with a thickness less than about 100 pm. However, mounting thin ceramic membranes on PPIC frames such that tension is applied thereto and thereby reducing out-of-plane deflection has proven challenging since ceramics exhibit reduced plasticity and deformation compared to polymers. Current PPIC development with ceramic membrane entry windows have focused on ring fixtures with complex engineering designs to maintain tension on the membrane surface and limit out-of-plane membrane deflection under operation conditions. Such ring fixtures are costly to fabricate and have provided limited success in providing tensioned ceramic membrane entry windows with minimal out-of-plane deflection.

[0007] In one embodiment a stiffened thin ceramic membrane comprises a membrane layer with a ceramic composition, a thickness less than or equal to about 100 pm, and a radius greater than or equal to about 20 mm and less than or equal to about 350 mm. A perimetrical glass frit rib is bonded to a first surface of the membrane layer and the perimetrical glass frit rib comprises a thickness between about 10 pm and about 200 pm, and a width of less than or equal to about 10 mm. The perimetrical glass frit rib may be spaced from a perimeter of the membrane layer by less than or equal to about 5 mm, for example less than or equal to about 2 mm, and the membrane layer with the perimetrical glass frit rib bonded to the first surface may comprise an out-of-plane deflection, per unit length, less than about 0.2 pm/mm. In embodiments, the perimetrical glass frit rib may have a width less than or equal to about 5 mm and a thickness between about 10 pm and about 100 pm. In some embodiments, the perimetrical glass frit rib bonded to the first surface comprises an out-of-plane deflection, per unit length, less than about 0.1 mih/mm. For example, the out-of-plane deflection, per unit length, may be less than about 1.0 x 10 ² pm/mm. The membrane layer may be formed from at least one of zirconia, yttria stabilized zirconia, alumina, aluminum nitride, silicon carbide, magnesium alumina spinel, mullite, cordierite and fused silica. Also, the perimetrical glass frit rib may be formed from a glass frit such that a coefficient of thermal expansion (CTE) mismatch between the perimetrical glass frit rib and the membrane layer is at least 2.0 x 10 ⁶ /°C. In some embodiments, the perimetrical glass frit rib may be formed from a glass frit such that a CTE mismatch between the perimetrical glass frit rib and the membrane layer is at least 4.0 x 10 ⁶ /°C. In the alternative, or in addition to, the perimetrical glass frit rib and the membrane layer may have a CTE mismatch between about 2.0 x 10 ⁶ /°C and about 6.0 x 10 ⁶ /°C.

[0008] In another embodiment, an entry window for a parallel-plate ionization chamber (PPIC) comprises a membrane layer with a ceramic composition, a thickness less than or equal to about 100 pm, and a radius greater than or equal to about 20 mm and less than or equal to about 350 mm. A perimetrical glass frit rib is bonded to a first surface of the membrane layer. The perimetrical glass frit rib may comprise a thickness between about 10 pm and about 200 pm and a width of less than or equal to about 10 mm. A polarizing electrode layer is bonded to a second surface of the membrane layer opposite the first surface. The perimetrical glass frit rib may be spaced from a perimeter of the membrane layer by less than or equal to about 5 mm, for example less than or equal to about 2 mm. The membrane layer with the perimetrical glass frit rib bonded to the first surface may comprise an out-of- plane deflection, per unit length, of less than about 0.2 pm/mm. The polarizing electrode layer may be a metal layer with a thickness less than or equal to about 10 pm and the perimetrical glass frit rib may have a width less than or equal to about 5 mm and a thickness between about 10 pm and about 100 pm. In some embodiments, the membrane layer with the perimetrical glass frit rib bonded to the first surface comprises an out-of-plane deflection, per unit length, less than about 0.1 pm/mm, for example less than about 1.0 x 10 ² pm/mm. In embodiments, a CTE mismatch between the perimetrical glass frit rib and the membrane layer may be at least 4.0 x 10 ⁶ /°C, for example at least 6.0 x 10 ⁶ /°C.

[0009] In another embodiment, a PPIC comprises an entry window with a polarizing electrode layer and a back wall with a collecting electrode layer spaced apart from the entry window by a distance equal to or less than about 2.0 mm. The entry window comprises a membrane layer with a ceramic composition, a thickness less than or equal to about 100 pm, and a radius greater than or equal to about 20 mm and less than or equal to about 350 mm. A perimetrical glass frit rib is bonded to a first surface of the membrane layer. The perimetrical glass frit rib comprises a thickness between about 10 pm and about 200 pm, and a width of less than or equal to about 10 mm. The polarizing electrode layer is bonded to a second surface of the membrane layer opposite the first surface. The perimetrical glass frit rib is spaced from a perimeter of the membrane layer by less than or equal to about 5 mm and the membrane layer with the perimetrical glass frit rib bonded to the first surface comprises an out-of-plane deflection, per unit length, less than about 0.2 pm/mm. A CTE mismatch between the perimetrical glass frit rib and the membrane layer may be at least 4.0 x 10 ⁶ /°C. In some embodiments, the perimetrical glass frit rib has a width less than or equal to about 5 mm and a thickness between about 10 pm and about 100 pm. Also, the membrane layer with the perimetrical glass frit rib bonded to the first surface may comprise an out-of-plane deflection, per unit length, less than about 0.1 pm/mm.

[0010] Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from the description or recognized by practicing the embodiments as described in the written description and claims hereof, as well as the appended drawings.

[0011] It is to be understood that both the foregoing general description and the following detailed description are merely exemplary, and are intended to provide an overview or framework to understand the nature and character of the claims. The accompanying drawings are included to provide a further understanding, and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiments, and together with the description serve to explain principles and operation of the various embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] FIG. 1 schematically depicts a perspective view of stiffened thin membrane according to one or more embodiments described herein;

[0013] FIG. 2 schematically depicts a view of section 2-2 in FIG. 1;

[0014] FIG. 3 schematically depicts a side cross-sectional view of a stiffened thin membrane according to one or more embodiments described herein; [0015] FIG. 4 schematically depicts a side cross-sectional view of a stiffened thin membrane according to one or more embodiments described herein;

[0016] FIG. 5 schematically depicts a side cross-sectional view of a stiffened thin membrane according to one or more embodiments described herein;

[0017] FIG. 6 schematically depicts a side cross-sectional view of a stiffened thin membrane according to one or more embodiments described herein;

[0018] FIG. 7 schematically depicts a side cross-sectional view of a parallel plate ionization chamber (PPIC) with a stiffened thin membrane according to one or more embodiments described herein;

[0019] FIG. 8A schematically depicts a top view of a testing apparatus for measuring out- of-plane deflection of a stiffened thin membrane according to one or more embodiments described herein; and

[0020] FIG. 8B schematically depicts a view of section 8B-8B in FIG. 8 A.

DETAILED DESCRIPTION

[0021] Referring to FIG. 1, a stiffened thin membrane 10 comprises a membrane layer 100 with a perimetrical glass frit rib 120, i.e., a rib 120 extending along or near a perimeter 102 of the surface of the membrane layer 100. The perimetrical glass frit rib 120 is disposed over and thermally bonded to the membrane layer 100. The membrane layer 100 comprises a first surface 101 (also referred to herein as an“upper surface 101” (+Y direction)) and a second surface 103 (also referred to herein as a“lower surface 103” (-Y direction)). The perimeter 102 of the membrane layer 100 extends along an outer edge (not labeled) of the membrane layer 100. The membrane layer 100 has a thickness‘W (Y direction) between the upper surface 101 and the lower surface 103 and a radius from a center point‘C’ of the membrane layer 100 to the perimeter 102. While the membrane layer 100 depicted in FIG. 1 has a circular shape, it should be understood that membrane layers with other geometrical shapes such as squares, rectangles, triangles, ellipses, and the like may be utilized and are included in the instant disclosure.

[0022] In embodiments, the perimetrical glass frit rib 120 comprises a lower surface 122 bonded to the upper surface 101 of the membrane layer 100, an upper surface 124 spaced apart from the lower surface 122, an outer surface 126 and an inner surface 128 spaced apart from the outer surface 126. As used herein, the phrase“outer surface” refers to a surface positioned outwardly from an inner surface relative to a center point C of a membrane layer and the phrase“inner surface” refers to a surface positioned inwardly from an outer surface relative to the center point C of the membrane layer. The perimetrical glass frit rib 120 has a thickness‘tr’ between the lower surface 122 and the upper surface 124, a width‘wf between the outer surface 126 and the inner surface 128, and an inner radius‘r_r’ from the center point C of the membrane layer 100 to the inner surface 128. Also, the outer surface 126 of the perimetrical glass frit rib 120 may be spaced or offset from the perimeter 102 of the membrane layer 100 by a distance Of’ that is less than or equal to 5 mm, for example, less than or equal to 2.5 mm, 1 mm, 0.5 or 0.1 mm. In some embodiments, perimetrical glass frit rib 120 may be positioned on the perimeter 102 of the membrane layer 100, i.e., the distance Of is equal to zero. In some embodiments, the perimetrical glass frit rib 120 may extend continuously along or near the perimeter 102. In other embodiments, the perimetrical glass frit rib 120 may extend non-continuously along or near a perimeter 102. That is, the perimetrical glass frit rib 120 may have one or more gaps so long as the perimetrical glass frit rib 120 provides a stiffness to the membrane layer 100 as described herein.

[0023] Referring to FIGS. 1 and 2, one or more additional layers may be disposed over and bonded to the membrane layer 100. Particularly, a polarizing electrode layer 110 may be bonded to the membrane layer 100. The polarizing electrode layer 110 comprises an upper surface 112, a lower surface 114, and a thickness‘te’ between the upper surface 112 and the lower surface 114. In embodiments, the upper surface 112 may be deposited onto the lower surface 103 of the membrane layer 100 using known electrode layer deposition techniques such as chemical vapor deposition (CVD) techniques, physical vapor deposition (PVD) techniques, and the like. As depicted in FIGS. 1 and 2, the polarizing electrode layer 110 may have generally the same radius r_m as the membrane layer 100.

[0024] In embodiments, the perimetrical glass frit rib 120 reduces out-of-plane deflection of the membrane layer 100 and the polarizing electrode layer 110 bonded to the membrane layer 100, per unit length, due to mechanical support (stiffening) provided by the perimetrical glass frit rib 120. As used herein, the phrase“out-of-plane deflection” refers to deflection of a membrane layer due to gravity and/or thermal stresses such that the membrane layer has an upper surface that does not lie on a single plane. In the alternative, or in addition to, the perimetrical glass frit rib 120 reduces out-of-plane deflection of the membrane layer 100 and the polarizing electrode layer 110 bonded to the membrane layer 100, per unit length, due to differences of thermal expansion and thermal contraction between the membrane layer 100 and the perimetrical glass frit rib 120 bonded to the membrane layer 100. Particularly, the perimetrical glass frit rib 120 may be formed from a material that is different than the membrane layer 100. Accordingly, the membrane layer 100 may have a first coefficient of thermal expansion (‘CTEi’) and the perimetrical glass frit rib 120 may have a second‘CTE₂’ that is different than the first coefficient of thermal expansion CTEi (i.e., CTEi ¹ CTE2). In some embodiments, the first CTEi of the membrane layer 100 is greater than the second CTE2 of the perimetrical glass frit rib 120 (i.e., CTEi > CTE2). In such embodiments, cooling the membrane layer 100 with the perimetrical glass frit rib 120 bonded thereto from an elevated temperature (e.g., a firing temperature of the membrane layer 100 and/or perimetrical glass frit rib 120) to ambient temperature (e.g., about 23°C) results in the perimetrical glass frit rib 120 contracting less than the membrane layer 100 thereby resisting contraction of the membrane layer 100. That is, the perimetrical glass frit rib 120 prevents the membrane layer 100 from fully contracting thereby resulting in a tensile strain and a corresponding tensile stress within the membrane layer 100. It should be understood that the tensile stress within the membrane layer 100 resists out-of-plane deflection (e.g., deflection due to gravity) of the membrane layer 100 as discussed in greater detail below.

[0025] In embodiments, the perimetrical glass frit rib 120, and other perimetrical glass frit ribs disclosed herein, reduces out-of-plane deflection of a membrane layer 100, per unit length, by at least 20%. For example, in some embodiments, the perimetrical glass frit rib 120, and other perimetrical glass frit ribs disclosed herein, may reduce the out-of-plane deflection of a membrane layer 100, per unit length, by at least 30%. In other embodiments, the perimetrical glass frit rib 120, and other perimetrical glass frit ribs disclosed herein, may reduce the out-of-plane deflection of a membrane layer 100, per unit length, by at least 40%. In still other embodiments, the perimetrical glass frit rib 120, and other perimetrical glass frit ribs disclosed herein, may reduce the out-of-plane deflection of a membrane layer 100, per unit length, by at least 50%. It should be understood that the perimetrical glass frit rib 120, and other perimetrical glass frit ribs disclosed herein, may reduce the out-of-plane deflection of a membrane layer 100, per unit length, between 20% and 50%. For example, in some embodiments, the perimetrical glass frit rib 120, and other perimetrical glass frit ribs disclosed herein, may reduce the out-of-plane deflection of a membrane layer 100, per unit length, between 20% and 30%. In other embodiments, the perimetrical glass frit rib 120, and other perimetrical glass frit ribs disclosed herein, may reduce the out-of-plane deflection of a membrane layer 100, per unit length, between 30% and 40%. In still other embodiments, the perimetrical glass frit rib 120, and other perimetrical glass frit ribs disclosed herein, may reduce the out-of-plane deflection of a membrane layer 100, per unit length, between 40% and 50%. In embodiments, the perimetrical glass frit rib 120 may be thermally bonded to the upper surface 101 of the membrane layer 100.

[0026] The thickness, length and width of the membrane layer 100 may depend on the intended use of the stiffened thin membrane 10. In embodiments, the membrane layer 100 may have a thickness tm within the range of about 10 pm and about 100 pm and a radius r_m within the range of about 10 mm and about 350 mm. In some embodiments, the thickness tm of the membrane layer 100 may be between about 10 pm and about 90 pm, for example between about 10 pm and 20 pm, between about 20 pm and 30 pm, between about 30 pm and 40 pm, between about 40 pm and 50 pm, between about 50 pm and 60 pm, between about 60 pm and 70 pm, between about 70 pm and 80 pm, or between about 80 pm and 90 pm. In such embodiments, the radius r_m of the membrane layer 100 may be between about 20 mm and about 300 mm, for example between about 20 mm and about 30 mm, between about 45 mm and about 55 mm, between about 65 mm and about 85 mm, between about 90 mm and about 110 mm, between about 115 mm and about 135 mm, between about 140 mm and about 160 mm, between about 180 mm and about 220 mm, or between about 280 mm and about 320 mm.

[0027] Similar to the thickness and radius of the membrane layer 100, the thickness and width of the perimetrical glass frit rib 120 may depend on the intended use of the stiffened thin membrane 10. In embodiments, the perimetrical glass frit rib 120, and other glass frit ribs described herein, may have a thickness tr between about 2 pm and about 100 pm and a width wr between about 0.1 mm and about 20 mm. In some embodiments, the thickness tr of the perimetrical glass frit rib 120, and other glass frit ribs described herein, may be between about 2 pm and about 75 pm, for example between about 2 pm and about 4 pm, between about 4 pm and about 6 pm, between about 8 pm and about 10 pm, between about 13 pm and about 17 pm, between about 18 pm and 22 pm, between about 23 pm and about 27 pm, between about 28 pm and about 32 pm, between about 33 pm and about 37 pm, between about 38 pm and about 42 pm, between about 43 pm and about 47 pm, between about 48 pm and about 52 mih, between about 58 mih and about 62 mih, between about 68 mih and about 72 mih, between about 78 mih and about 82 mih, between about 88 mih and about 92 mih, or between about 98 mih and about 100 mih. In such embodiments, the width wr of the perimetrical glass frit rib 120 may be between about 0.2 mm and about 15 mm, for example between about 0.2 mm and about 0.4 mm, between about 0.4 mm and about 0.6 mm, between about 0.8 mm and about 1.2 mm, between about 1.8 mm and about 2.2 mm, between about 2.8 mm and about 3.2 mm, between about 3.8 mm and about 4.2 mm, between about 4.8 mm and about 5.2 mm, between about 5.8 mm and about 6.2 mm, between about 6.8 mm and about 7.2 mm, between about 7.8 mm and about 8.2 mm, between about 8.8 mm and about 9.2 mm, or between about 9.8 mm and about 10.2 mm.

[0028] In embodiments, the perimetrical glass frit rib 120 provides a membrane layer 100 with an out-of-plane deflection (e.g., a gravitational deflection) less than or equal to about 10.0 pm. In some embodiments, the perimetrical glass frit rib 120 provides a membrane layer 100 with an out-of-plane deflection (e.g., a gravitational deflection) less than or equal to about 5.0 pm, for example, less than or equal to about 2.5 pm. Also, in embodiments, the perimetrical glass frit rib 120 provides a membrane layer 100 with an out-of-plane deflection, per unit length, less than about 0.2 pm/mm, for example less than about 0.1 pm/mm, less than about 1.0 x 10 ² pm/mm, less than about 5.0 x 10 ³ pm/mm, less than about 2.5 x 10 ³ pm/mm or less than about 2.0 x 10 ³ pm/mm. Particularly, the out-of-plane deflection, per unit length, may be between about 0.2 pm/mm and about 0.1 pm/mm, between about 0.1 pm/mm and about 1.0 x 10 ² pm/mm, between about 1.0 x 10 ² pm/mm and about 5.0 x 10 ³ pm/mm, between about 5.0 x 10 ³ pm/mm and about 2.5 x 10 ³ pm/mm, or between about 2.5 x 10 ³ pm/mm and about 2.0 x 10 ³ pm/mm.

[0029] The membrane layer 100 may be formed from materials suitable for the transmission of x-ray electromagnetic radiation there through and yet resistant to x-ray electromagnetic radiation damage. Non-limiting examples of materials used to form the membrane layer 100 include ceramics such as zirconia, yttria stabilized zirconia, alumina, aluminum nitride, silicon carbide, magnesium alumina spinel, mullite, cordierite and fused silica. The Young’s Modulus and CTE for such materials within the temperature range of about 40°C and about 400°C is shown in Table 1 below.

Table 1.

Membrane Material Young’s Modulus (GPa) CTE (x 10 ⁶ /°Q

[0030] The perimetrical glass frit rib 120, and other glass frit ribs described herein, may be formed from materials suitable for depositing onto thin ceramic, glass or ceramic/glass membrane layers and being sintered to form a stiffening rib. Non-limiting examples of materials used to form the perimetrical glass frit rib 120 include glass frit available from Corning Inc. such as alkali barium glass frit (Coming Code: 9013), alkali borosilicate glass frit (Coming Code: 7056) , borosilicate glass frit (Coming Code: 7052), borosilicate glass frit (Corning Code: 7070), soda borosilicate glass frit (Corning Code: 7740), and soda zirconium silicate (Coming Code: 1890). The CTE for such materials within the temperature range of about 0°C and about 300°C is in Table 2 below.

Table 2.

In embodiments, the perimetrical glass frit rib 120 is formed from a glass frit comprising a CTE that is at least 2.0 x 10 ⁶ /°C less than the CTE of the membrane layer 100. For example, the perimetrical glass frit rib 120 may be formed from a glass frit with a CTE that is at least 4.0 x 10 ⁶ /°C less than the CTE of the membrane layer 100 or at least 6.0 x 10 ⁶ /°C less than the CTE of the membrane layer 100. Particularly, the perimetrical glass frit rib 120 may be formed from a glass frit with a CTE that is between about 2.0 x 10 ⁶ /°C and about 3.0 x 10 ⁶ /°C less than the CTE of the membrane layer 100, between about 3.0 x 10 ⁶ /°C and about 4.0 x 10 ⁶ /°C less than the CTE of the membrane layer 100, between about 4.0 x 10 ⁶ /°C and about 5.0 x 10 ⁶ /°C less than the CTE of the membrane layer 100, between about 5.0 x 10 ⁶ /°C and about 6.0 x 10 ⁶ /°C less than the CTE of the membrane layer 100, or between about 6.0 x 10 ⁶ /°C and about 8.0 x 10 ⁶ /°C less than the CTE of the membrane layer 100. Accordingly, a CTE mismatch between the perimetrical glass frit rib 120 and the membrane layer 100 may be between about 2.0 x 10 ⁶ /°C and about 8.0 x 10 ⁶ /°C. In some embodiments, the CTE mismatch between the perimetrical glass frit rib 120 and the membrane layer 100 may be between about 2.0 x 10 ⁶ /°C and about 6.0 x 10 ⁶ /°C. It should be understood the Young’s modulus of the membrane layer 100 may be taken into consideration when selecting a glass frit material such that a CTE mismatch between the membrane layer 100 and the perimetrical glass frit rib 120, and other perimetrical glass frit ribs disclosed herein, does not result in plastic deformation of the membrane layer 100 during cooling of the stiffened thin membrane 10.

[0031] The polarizing electrode layer 110 may be formed from materials suitable for conducting electrical current. Non-limiting examples of electrode layer materials include platinum (Pt), gold (Au), copper (Cu), aluminum (Al), titanium (Ti), or combinations thereof. In embodiments, the polarizing electrode layer 110, and other electrode layers described herein, may have a thickness t_e between about 0.2 pm and about 10 pm. In some embodiments, the thickness t_e of the polarizing electrode layer 110 may be between about 0.5 pm and about 5 pm, for example between about 0.5 pm and about 1 pm, between about 1 pm and about 2 pm, between about 2 pm and about 3 pm, between about 3 pm and about 4 pm, or between about 4 pm and 5 pm.

[0032] Referring now to FIG. 3, in embodiments, a stiffened thin membrane 12 may comprise an additional glass frit rib disposed over and bonded to the membrane layer 100. Particularly, the perimetric glass frit rib 120 may be a first perimetric glass frit rib 120 disposed over the upper surface 101 of the membrane layer 100 and a second perimetric glass frit rib 130 may be disposed over the lower surface 103 as schematically depicted in FIG. 3. In embodiments, the second perimetrical glass frit rib 130 comprises a lower surface 132, an upper surface 134 spaced apart from the lower surface 132 and bonded to the lower surface 103 of the membrane layer 100, an outer surface 136 and an inner surface 138 spaced apart from the outer surface 136. The outer surface 136 of the second perimetrical glass frit rib 130 may be spaced or offset (not labeled) from the perimeter 102 of the membrane layer 100 by a distance that is less than or equal to about 5.0 mm, for example, less than or equal to about 2.5 mm, 1.0 mm, 0.5 or 0.1 mm. In some embodiments, the second perimetrical glass frit rib 130 may be positioned on the perimeter 102 of the membrane layer 100. Also, the second perimetrical glass frit rib 130 may extend continuously along or near the perimeter 102. In the alternative, the second perimetrical glass frit rib 130 may extend non-continuously along or near a perimeter 102. That is, the second perimetrical glass frit rib 130 may have one or more gaps so long as the perimetrical glass frit rib 130 provides a stiffness to the membrane layer 100 as described herein.

[0033] Still referring to FIG. 3, and similar to the first perimetrical glass frit rib 120, the second perimetrical glass frit rib 130 may assist in reducing out-of-plane deflection of the membrane layer 100 and the polarizing electrode layer 110 bonded to the membrane layer 100, per unit length, due to mechanical support (stiffening) provided by the second perimetrical glass frit rib 130 and/or differences of thermal expansion and thermal contraction between the membrane layer 100 and the second perimetrical glass frit rib 130 bonded to the membrane layer 100. Particularly, the second perimetrical glass frit rib 130 may be formed from a material that is different than the membrane layer 100. Accordingly, the membrane layer 100 may have a first coefficient of thermal expansion (‘CTEi’), the first perimetrical glass frit rib 120 may have a second‘CTEri’ that is different than the first coefficient of thermal expansion CTEi (i.e., CTEi ¹ CTE2), and the second perimetrical glass frit rib 130 may have a third‘CTE₃’ that is different than the first coefficient of thermal expansion CTEi (i.e., CTEi ¹ CTE3). In some embodiments, the second perimetrical glass frit rib 130 is formed from the same material as the first perimetrical glass frit rib 120 and the third CTE3 is generally equal to the second CTE2 (i.e., CTEi ¹ CTE2 = CTE3). In other embodiments, the second perimetrical glass frit rib 130 is not formed from the same material as the first perimetrical glass frit rib 120 and the third CTE3 is not generally equal to the second CTE2 (i.e., CTEi ¹ CTE2 ¹ CTE3). In some embodiments, the first CTEi of the membrane layer 100 is greater than the third CTE3 of the second perimetrical glass frit rib 130 (i.e., CTEi > CTE3). In such embodiments, cooling the membrane layer 100 with the first perimetrical glass frit rib 120 and the second perimetrical glass frit rib 130 from an elevated temperature results in the first and second perimetrical glass frit ribs 120, 130 contracting less than the membrane layer 100. Accordingly, the first and second perimetrical glass frit ribs 120, 130 resist the contraction of the membrane layer 100 thereby resulting in a tensile strain and a corresponding tensile stress within the membrane layer 100. The tensile stress within the membrane layer resists gravitational deflection of the membrane layer 100.

[0034] In embodiments, the polarizing electrode layer 110 may be disposed over the second perimetrical glass frit rib 130 and the lower surface 103 of the membrane layer 100. For example, the polarizing electrode layer 110 may be deposited onto the lower surface 132, outer surface 136, and inner surface 138 of the second perimetrical glass frit rib 130 and the lower surface 103 of the membrane layer 100 as depicted in FIG. 3.

[0035] In embodiments, the pair of perimetrical glass frit ribs 120, 130 provide a membrane layer 100 with an out-of-plane deflection (e.g., a gravitational deflection) less than or equal to about 10.0 pm. In some embodiments, the pair of perimetrical glass frit ribs 120, 130 provide a membrane layer 100 with an out-of-plane deflection (e.g., a gravitational deflection) less than or equal to about 5.0 pm, for example, less than or equal to about 2.5 pm. Also, in embodiments, the pair of perimetrical glass frit ribs 120, 130 provide a membrane layer 100 with an out-of-plane deflection, per unit length, less than about 0.2 pm/mm, for example less than about 0.1 pm/mm, less than about 1.0 x 10 ² pm/mm, less than about 5.0 x 10 ³ pm/mm, less than about 2.5 x 10 ³ pm/mm or less than about 2.0 x 10 ³ pm/mm. Particularly, the out-of-plane deflection, per unit length, may be between about 0.2 pm/mm and about 0.1 pm/mm, between about 0.1 pm/mm and about 1.0 x 10 ² pm/mm, between about 1.0 x 10 ² pm/mm and about 5.0 x 10 ³ pm/mm, between about 5.0 x 10 ³ pm/mm and about 2.5 x 10 ³ pm/mm, or between about 2.5 x 10 ³ pm/mm and about 2.0 x 10 ³ pm/mm.

[0036] While FIGS. 1-3 schematically depict the perimetrical glass frit ribs with a rectangular cross-section, stiffened thin membranes may comprise perimetrical glass frit ribs with cross-sections that are not rectangular. For example, and referring to FIG. 4, a stiffened thin membrane 14 comprises a perimetrical glass frit rib 140 with a triangular cross-section. Particularly, an upper (+Y direction) perimetrical glass frit rib 140 with a triangular cross- section may be bonded to the upper surface 101 of the membrane layer 100. In some embodiments, a lower (-Y direction) perimetrical glass frit rib 140 with a triangular cross- section may be bonded to the lower surface 103 of the membrane layer 100. Each of the perimetrical glass frit ribs 140 has an outer surface 146 and an inclined surface 148 extending from the outer surface 146 to the membrane layer 100. That is, the inclined surface 148 of the upper perimetrical glass frit rib 140 extends from the outer surface 146 to the upper surface 101 and the inclined surface 148 of the lower perimetrical glass frit rib 140 extends from the outer surface 146 to the lower surface 103 as depicted in FIG. 4. Each of the perimetrical glass frit ribs 140 have a thickness tr (only one shown in FIG. 4) and a width wr (only one shown in FIG. 4). In embodiments, the polarizing electrode layer 110 may be disposed over the lower perimetrical glass frit rib 140 and the lower surface 103 of the membrane layer 100. For example, the polarizing electrode layer 110 may be deposited onto the inclined surface 148 of the lower perimetrical glass frit rib 140 and the lower surface 103 of the membrane layer 100 as depicted in FIG. 4.

[0037] In embodiments, the perimetrical glass frit rib 140 and/or the pair of perimetrical glass frit ribs 140 provide a membrane layer 100 with an out-of-plane deflection (e.g., a gravitational deflection) less than or equal to about 10.0 pm. In some embodiments, the perimetrical glass frit rib 140 and/or the pair of perimetrical glass frit ribs 140 provide a membrane layer 100 with an out-of-plane deflection (e.g., a gravitational deflection) less than or equal to about 5.0 pm, for example, less than or equal to about 2.5 pm. Also, in embodiments, the perimetrical glass frit rib 140 and/or the pair of perimetrical glass frit ribs 140 provide a membrane layer 100 with an out-of-plane deflection, per unit length, less than about 0.2 pm/mm, for example less than about 0.1 pm/mm, less than about 1.0 x 10 ² pm/mm, less than about 5.0 x 10 ³ pm/mm, less than about 2.5 x 10 ³ pm/mm or less than about 2.0 x 10 ³ pm/mm. Particularly, the out-of-plane deflection, per unit length, may be between about 0.2 pm/mm and about 0.1 pm/mm, between about 0.1 pm/mm and about 1.0 x 10 ² pm/mm, between about 1.0 x 10 ² pm/mm and about 5.0 x 10 ³ pm/mm, between about 5.0 x 10 ³ pm/mm and about 2.5 x 10 ³ pm/mm, or between about 2.5 x 10 ³ pm/mm and about 2.0 x 10 ³ pm/mm.

[0038] Referring now to FIG. 5, in embodiments, a stiffened thin membrane 16 comprises a perimetrical glass frit rib 160 with an arcuate cross-section. Particularly, an upper (+Y direction) perimetrical glass frit rib 160 with an arcuate cross-section (e.g., a parabolic cross- section) may be bonded to the upper surface 101 of the membrane layer 100. In some embodiments, a lower (-Y direction) perimetrical glass frit rib 160 with an arcuate cross- section may be bonded to the lower surface 103 of the membrane layer 100. Each of the perimetrical glass frit ribs 160 has an outer surface 166 and an arcuate surface 168 (e.g., a parabolic shaped surface) extending from the outer surface 166 to the membrane layer 100. That is, the arcuate surface 168 of the upper perimetrical glass frit rib 160 extends from the outer surface 166 to the upper surface 101 and the arcuate surface 168 of the lower perimetrical glass frit rib 160 extends from the outer surface 166 to the lower surface 103 as depicted in FIG. 5. Each of the perimetrical glass frit ribs 160 has a thickness tr (only one shown in FIG. 5) and a width wr (only one shown in FIG. 5). In embodiments, the polarizing electrode layer 110 may be disposed over the lower perimetrical glass frit rib 160 and the lower surface 103 of the membrane layer 100. For example, the polarizing electrode layer 110 may be deposited onto the arcuate surface 168 of the lower perimetrical glass frit rib 160, and the lower surface 103 of the membrane layer 100 as depicted in FIG. 5.

[0039] In embodiments, the perimetrical glass frit rib 160 and/or the pair of perimetrical glass frit ribs 160 provide a membrane layer 100 with an out-of-plane deflection (e.g., a gravitational deflection) less than or equal to about 10.0 pm. In some embodiments, the perimetrical glass frit rib 160 and/or the pair of perimetrical glass frit ribs 160 provide a membrane layer 100 with an out-of-plane deflection (e.g., a gravitational deflection) less than or equal to about 5.0 pm, for example, less than or equal to about 2.5 pm. Also, in embodiments, the perimetrical glass frit rib 160 and/or the pair of perimetrical glass frit ribs 160 provide a membrane layer 100 with an out-of-plane deflection, per unit length, less than about 0.2 pm/mm, for example less than about 0.1 pm/mm, less than about 1.0 x 10 ² pm/mm, less than about 5.0 x 10 ³ pm/mm, less than about 2.5 x 10 ³ pm/mm or less than about 2.0 x 10 ³ pm/mm. Particularly, the out-of-plane deflection, per unit length, may be between about 0.2 pm/mm and about 0.1 pm/mm, between about 0.1 pm/mm and about 1.0 x 10 ² pm/mm, between about 1.0 x 10 ² pm/mm and about 5.0 x 10 ³ pm/mm, between about 5.0 x 10 ³ pm/mm and about 2.5 x 10 ³ pm/mm, or between about 2.5 x 10 ³ pm/mm and about 2.0 x 10 ³ pm/mm.

[0040] Referring now to FIG. 6, in embodiments, a stiffened thin membrane 18 comprises a perimetrical glass frit rib 180 with a combined rectangular-triangular cross-section. Particularly, an upper (+Y direction) perimetrical glass frit ribs 180 with a first portion 182 comprising a rectangular cross-section and a second portion 184 comprising a triangular cross-section may be bonded to the upper surface 101 of the membrane layer 100. In some embodiments, a lower (-Y direction) perimetrical glass frit ribs 180 with a first portion comprising a rectangular cross-section (not labeled in FIG. 6) and a second portion comprising a triangular cross-section (not labeled in FIG. 6) may be bonded to the lower surface 103 of the membrane layer 100. The upper (+Y direction) perimetrical glass frit rib 180 has an outer surface 186, an upper surface 187 extending from the outer surface 186, and an inclined surface 188 extending from the upper surface 187 to the upper surface 101 of the membrane layer 100. The lower (-Y direction) perimetrical glass frit rib 180 has an outer surface 186, a lower surface 189 extending from the outer surface 186, and an inclined surface 188 extending from the lower surface 189 to the lower surface 103 of the membrane layer 100. Each of the perimetrical glass frit ribs 180 has a thickness tr (only one shown in FIG. 6), a first width wu of the first portion 182, and a second width Wr2 of the second portion 184 (only one shown in FIG. 6). In embodiments, the polarizing electrode layer 110 may be disposed over the lower perimetrical glass frit rib 180 and the lower surface 103 of the membrane layer 100. For example, the polarizing electrode layer 110 may be deposited onto the lower surface 189 and the inclined surface 188 of the lower perimetrical glass frit rib 180, and the lower surface 103 of the membrane layer 100 as depicted in FIG. 6.

[0041] In embodiments, the perimetrical glass frit rib 180 and/or the pair of perimetrical glass frit ribs 180 provide a membrane layer 100 with an out-of-plane deflection (e.g., a gravitational deflection) less than or equal to about 10.0 pm. In some embodiments, the perimetrical glass frit rib 180 and/or the pair of perimetrical glass frit ribs 180 provide a membrane layer 100 with an out-of-plane deflection (e.g., a gravitational deflection) less than or equal to about 5.0 pm, for example, less than or equal to about 2.5 pm. Also, in embodiments, the perimetrical glass frit rib 180 and/or the pair of perimetrical glass frit ribs 180 provide a membrane layer 100 with an out-of-plane deflection, per unit length, less than about 0.2 pm/mm, for example less than about 0.1 pm/mm, less than about 1.0 x 10 ² pm/mm, less than about 5.0 x 10 ³ pm/mm, less than about 2.5 x 10 ³ pm/mm or less than about 2.0 x 10 ³ pm/mm. Particularly, the out-of-plane deflection, per unit length, may be between about 0.2 pm/mm and about 0.1 pm/mm, between about 0.1 pm/mm and about 1.0 x 10 ² pm/mm, between about 1.0 x 10 ² pm/mm and about 5.0 x 10 ³ pm/mm, between about 5.0 x 10 ³ pm/mm and about 2.5 x 10 ³ pm/mm, or between about 2.5 x 10 ³ pm/mm and about 2.0 x 10 ³ pm/mm.

[0042] Referring now to FIG. 7, embodiments of a parallel plate ionization chamber 20 with a stiffened thin membrane 12 utilized as an entry window comprising a membrane layer 100 with a perimetrical glass frit rib 120 (not shown) and a polarizing electrode layer 110 are schematically depicted. A back wall 190 is spaced apart from the entry window 22. A housing 194 positions and secures the entry window 22 and the back wall 190 a fixed distance Ή’ apart from each other (e.g., 2 mm). Air, or some other gas, may be between the entry window 22 and the back wall 190. A collector electrode layer 192 may be disposed over the back wall 190. A first electrical lead 116 may extend from and be in electrical contact with the polarizing electrode layer 110 and a second electrical lead 196 may extend from and be in electrical contact with the back wall 190. In operation, a voltage potential is applied between the polarizing electrode layer 110 and the collector electrode layer 192 thereby creating an electric field in the air between the membrane layer 100 and the back wall 190. Electromagnetic radiation, e.g., x-ray radiation, propagates through the membrane layer 100 and the polarizing electrode layer 110 into the air volume between the membrane layer 100 and the back wall 190. The electromagnetic radiation results in ion-pairs comprising resultant positive ions and dissociate electrons moving to electrodes of opposite polarity. The flow of the ions and electrons to electrodes of opposite polarity generate an ionization current and the magnitude of the ionization current is a measure of the x-ray radiation propagating through the entry window 22, i.e., magnitude of the ionization current is a measure of the x- ray dosage. Out-of-plane deflection of the membrane layer 100 may be the result of gravity and/or movement of the PPIC 20 and an out-of-plane deflection greater than 10 pm may be undesirable.

EXAMPLES

[0043] Modeling of out-of-plane deflection for various membrane layer/perimetrical glass frit rib configurations was performed. For example, out-of-plane deflection of stiffened thin membranes 10 upon cooling from a firing temperature as a function of different offset Of of the perimetrical glass frit rib 120 from the perimeter 102, and different widths wr and thicknesses tr of the perimetrical glass frit rib 120 was modeled (see Examples 1 and 2 below). Out-of-plane deflection of stiffened thin membranes 10 upon cooling from a firing temperature and placement of the stiffened thin membrane 10 in a fixture representing a housing 194 of a PPIC 20, as a function of different offset Of of the perimetrical glass frit rib 120 from the perimeter 102, and different widths Wr and thicknesses tr of the perimetrical glass frit rib 120, was modeled (see Example 3 below). Out-of-plane deflection of stiffened thin membranes 12 upon cooling from a firing temperature as a function of different offset Of of the pair perimetrical glass frit ribs 120 from the perimeter 102, and different widths Wr and thicknesses tr of the perimetrical glass frit ribs 120 after cooling from a firing temperature was modeled (see Example 4 below).

Example 1

[0044] Cooling of stiffened thin membranes 10 (FIG. 2) comprising a membrane layer 100 with a diameter equal to 69.85 mm (2.75 inches), a perimetrical glass frit rib 120 bonded to the upper surface 101, and a 1.0 pm thick titanium polarizing electrode layer 110 (i.e., t_e = 1.0 pm) bonded to the lower surface 103 was modeled. Each of the membrane layers 100 were formed from zirconia - 3 mole % yttria and had a thickness tm equal to 20 pm. The perimetrical glass frit ribs 120 were offset from the perimeter 102 by 0.5 mm. The width of the perimetrical glass frit ribs 120 ranged from 0.5 mm to 2.0 mm and the thickness of the perimetrical glass frit rib 120 ranged from 10 pm to 50 pm. Out-of-plane deflection and stress at the center C of the membrane layer 100 were calculated after cooling the stiffened thin membranes 10 from 900°C to 20°C. Table 1 below shows the out-of-plane deflection and stress for each of the membrane layer 100 - perimetrical glass frit rib 120 combinations.

Table 1.

Particularly, a membrane layer 100 with a perimetrical glass frit rib 120 comprising a width of 0.5 mm and thicknesses between 10 pm, 20 pm, 30 pm and 50 pm had out-of-plane deflections of 97 pm, 96 pm, 94 pm and 103 pm, respectively, and stresses of 23 MPa, 37 MPa, 51 MPa and 77 MPa, respectively. The membrane layer 100 with a perimetrical glass frit rib 120 comprising a width of 1.0 mm and thicknesses between 10 pm, 20 pm, 30 pm and 50 pm had out-of-plane deflections of 191 pm, 173 pm, 152 pm and 137 pm, respectively, and stresses of 38 MPa, 65 MPa, 91 MPa and 140 MPa, respectively. The membrane layer 100 with a perimetrical glass frit rib 120 comprising a width of 2.0 mm and thicknesses between 10 mih, 20 mih, 30 mih and 50 mih had out-of-plane deflections of 324 mih, 305 mih, 263 mih and 206 mih, respectively, and stresses of 63 MPa, 120 MPa, 166 MPa and 250 MPa, respectively.

Example 2

[0045] Cooling of stiffened thin membranes 10 (FIG. 2) comprising a membrane layer 100 with a diameter equal to 101.6 mm (4.0 inches), a perimetrical glass frit rib 120 bonded to the upper surface 101, and a 1.0 pm thick titanium polarizing electrode layer 110 (i.e., te = 1.0 pm) bonded to the lower surface 103 was modeled. Each of the membrane layers 100 were formed from zirconia - 3 mole % yttria and had a thickness tm equal to 20 pm. The perimetrical glass frit ribs 120 were offset from the perimeter 102 by either 0.0 mm or 0.5 mm. The width of the perimetrical glass frit ribs 120 ranged from 0.5 mm to 3.0 mm and the thickness of the perimetrical glass frit rib 120 ranged from 10 pm to 50 pm. Out-of-plane deflection and stress at the center C of the membrane layer 100 were calculated after cooling the stiffened thin membranes 10 from 900°C to 20°C. Table 2 below shows the out-of-plane deflection and stress for each of the membrane layer 100 - perimetrical glass frit rib 120 combinations.

Table 2.

Particularly, a membrane layer 100 with a perimetrical glass frit rib 120 offset 0.0 mm from the perimeter 102 and comprising a width of 1.0 mm and thicknesses between 10 pm, 20 pm, 30 pm and 50 pm had out-of-plane deflections of 84 pm, 79 pm, 74 pm and 77 pm, respectively, and stresses of 28 MPa, 46 MPa, 64 MPa and 99 MPa, respectively. The corresponding out-of-plane deflections per unit length (i.e., out-of-plane deflection/50.8 mm) for the membrane layer 100 with the perimetrical glass frit rib 120 offset 0.0 mm from the perimeter 102 and comprising the width of 1.0 mm and thicknesses between 10 pm, 20 pm, 30 pm and 50 pm were 1.65 pm/mm, 1.56 pm/mm, 1.46 pm/mm, and 1.52 pm/mm, respectively. For comparison, the out-of-plane deflection of the membrane layer 100 without a perimetrical glass frit rib 120 was 168 pm and the out-of-plane deflection, per unit length, of the membrane layer 100 without a perimetrical glass frit rib 120 was 3.31 pm/mm. Accordingly, the perimetrical glass frit rib 120 offset 0.0 mm from the perimeter 102 and comprising the width of 1.0 mm and thicknesses between 10 pm, 20 pm, 30 pm and 50 pm reduced the out-of-plane deflection, per unit length, of the membrane layer 100 by 50.2%, 52.9%, 55.9%, and 54.1% respectively. The membrane layer 100 with a perimetrical glass frit rib 120 offset 0.0 mm from the perimeter 102 and comprising a width of 2.0 mm and thicknesses between 10 pm, 20 pm, 30 pm and 50 pm had out-of-plane deflections of 212 pm, 185 pm, 153 pm and 130 pm, respectively, and stresses of 48 MPa, 84 MPa, 117 MPa and 180 MPa, respectively. The membrane layer 100 with a perimetrical glass frit rib 120 offset 0.5 mm from the perimeter 102 and comprising a width of 0.5 mm and thicknesses between 10 pm, 20 pm, 30 pm and 50 pm had out-of-plane deflections of 91 pm, 91 pm, 89 pm and 96 pm, respectively, and stresses of 18 MPa, 28 MPa, 37 MPa and 56 MPa, respectively. Also, the out-of-plane deflections, per unit length, for the membrane layer 100 with a perimetrical glass frit rib 120 offset 0.5 mm from the perimeter 102 and comprising a width of 0.5 mm and thicknesses between 10 pm, 20 pm, 30 pm and 50 pm was 1.79 pm/mm, 1.79 pm/mm, 1.75 pm/mm and 1.89 pm/mm, respectively. Accordingly, the perimetrical glass frit rib 120 offset 0.5 mm from the perimeter 102 and comprising the width of 0.5 mm and thicknesses between 10 pm, 20 pm, 30 pm and 50 pm reduced the out-of- plane deflection, per unit length, of the membrane layer 100 by 45.9%, 45.9%, 47.1%, and 42.9% respectively. The membrane layer 100 with a perimetrical glass frit rib 120 offset 0.5 mm from the perimeter 102 and comprising a width of 1.0 mm and thicknesses between 10 pm, 20 pm, 30 pm and 50 pm had out-of-plane deflections of 196 pm, 174 pm, 150 pm and 133 pm, respectively, and stresses of 28 MPa, 47 MPa, 65 MPa and 100 MPa, respectively. The membrane layer 100 with a perimetrical glass frit rib 120 offset 0.5 mm from the perimeter 102 and comprising a width of 2.0 mm and thicknesses between 10 pm, 20 pm, 30 pm and 50 pm had out-of-plane deflections of 360 pm, 326 pm, 273 pm and 207 pm, respectively, and stresses of 50 MPa, 85 MPa, 118 MPa and 181 MPa, respectively. The membrane layer 100 with a perimetrical glass frit rib 120 offset 0.5 mm from the perimeter 102 and comprising a width of 3.0 mm and thicknesses between 10 pm, 20 pm, 30 pm and 50 pm had out-of-plane deflections of 462 pm, 439 pm, 380 pm and 286 pm, respectively, and stresses of 70 MPa, 122 MPa, 169 MPa and 253 MPa, respectively.

Example 3

[0046] Cooling of stiffened thin membranes 10 (FIG. 2) mounted within a ring support 200 (FIGS. 8 A and 8B) designed to replicate a housing 194 of a PPIC 20 was modeled. The stiffened thin membranes 10 comprised a membrane layer 100 with a diameter equal to 4.0 inches (101.6 mm), a perimetrical glass frit rib 120 bonded to the upper surface 101, and a 1.0 pm thick titanium polarizing electrode layer 110 (i.e., t_e = 1.0 pm) bonded to the lower surface 103. Each of the membrane layers 100 were formed from zirconia - 3 mole % yttria and had a thickness tm equal to 20 pm. The perimetrical glass frit ribs 120 were offset from the perimeter 102 by 0.5 mm. The width of the perimetrical glass frit ribs 120 ranged from 0.5 mm to 1.0 mm and the thickness of the perimetrical glass frit rib 120 ranged from 30 pm to 50 pm. Out-of-plane deflection and stress at the center C of the membrane layer 100 were calculated after cooling the stiffened thin membranes 10 from 900°C to 20°C and mounting the stiffened thin membranes 10 in the ring support 200 schematically depicted in FIGS. 8 A and 8B. The ring support 200 comprised a lower ring 210 with an outer surface 212 and an inner surface 214, and an upper ring 220 with an outer surface 222 and an inner surface 224. The lower ring 210 has a height‘hl’ and the upper ring has a channel 226 for a perimetrical glass frit rib 120 to be disposed within. Placement of the thin stiffened membranes 10 between the lower ring 210 and the upper ring 220 exerts a force on an area proximal the perimeter 102 thereby flattening and reducing the out-of-plane deflection of the membrane layer 100. Table 3 below shows the out-of-plane deflection and stress for each of the membrane layer 100 - perimetrical glass frit rib 120 combinations.

Table 3.

Particularly, mounting a membrane layer 100 with a perimetrical glass frit rib 120 with an offset 0.5 mm from the perimeter 102 and comprising a width of 0.5 mm and a thickness of 50 pm within the ring support 200 decreased the out-of-plane deflection from 96 pm to 2 pm. Also, mounting a membrane layer 100 with a perimetrical glass frit rib 120 with an offset 0.5 mm from the perimeter 102 and comprising a width of 1.0 mm and a thickness of 50 pm within the ring support 200 decreased the out-of-plane deflection from 133 pm to 1 pm. Mounting a membrane layer 100 with a perimetrical glass frit rib 120 offset 0.5 mm from the perimeter 102 and comprising a width of 1.0 mm and a thickness of 30 pm within the ring support 200 decreased the out-of-plane deflection from 150 pm to 25 pm. Accordingly, in embodiments, the perimetrical glass frit rib 120 in combination with a support ring or frame provides a membrane layer 100 with an out-of-plane deflection less than about 10.0 pm. For example, the perimetrical glass frit rib 120 in combination with a support ring or frame may provide a membrane layer 100 with an out-of-plane deflection less than about 8.0 pm, less than about 6.0 pm, less than about 4.0 pm, or less than about 2.0 pm. Particularly, the out- of-plane deflection may be between about 10.0 pm and about 8.0 pm, between about 8.0 pm and about 6.0 pm, between about 6.0 pm and about 4.0 pm, between about 4.0 pm and about 2.0 pm, or between about 2.0 pm and about 1.0 pm.

Example 4

[0047] Cooling of stiffened thin membranes 12 (FIG. 3) comprising a membrane layer 100 with a diameter equal to 4.0 inches (101.6 mm), an upper perimetrical glass frit rib 120 bonded to the upper surface 101, a lower perimetrical glass frit rib 120 bonded to the lower surface 103, and a 1.0 pm thick titanium polarizing electrode layer 110 (i.e., t_e = 1.0 pm) bonded to the lower surface 103 was modeled. Each of the membrane layers 100 were formed from zirconia - 3 mole % yttria and had a thickness tm equal to 20 pm. The upper and lower perimetrical glass frit ribs 120 were offset from the perimeter 102 by either 0.0 mm or 0.5 mm. The width of the upper and lower perimetrical glass frit ribs 120 ranged from 0.5 mm to 2.0 mm and the thickness of the perimetrical glass frit rib 120 ranged from 10 pm to 50 pm. Out-of-plane deflection and stress at the center C of the membrane layer 100 were calculated after cooling the stiffened thin membranes 10 from 900°C to 20°C. Table 4 below shows the out-of-plane deflection and stress for each of the membrane layer 100 - perimetrical glass frit rib 120 combinations.

Table 4.

Particularly, a membrane layer 100 with lower and upper perimetrical glass frit ribs 120 offset 0.0 mm from the perimeter 102 and comprising a width of 0.5 mm and a thickness of 50 pm had an out-of-plane deflection of 0.5 pm, an out-of-plane deflection per unit length of 9.84 x 10 ³ pm/mm, and a stress of 81 MPa. The membrane layer 100 with upper and lower perimetrical glass frit ribs 120 offset 0.0 mm from the perimeter 102 and comprising a width of 0.5 mm and a thickness of 10 pm had an out-of-plane deflection of 2.4 pm, an out-of-plane deflection per unit length of 4.72 x 10 ² pm/mm, and a stress of 17 MPa. The membrane layer 100 with upper and lower perimetrical glass frit ribs 120 offset 0.0 mm from the perimeter 102 and comprising a width of 2.0 mm and a thickness of 10 pm had an out-of- plane deflection of 0.8 pm, an out-of-plane deflection per unit length of 1.57 x 10 ³ pm/mm, and a stress of 63 MPa. The membrane layer 100 with upper and lower perimetrical glass frit ribs 120 offset 0.5 mm from the perimeter 102 and comprising a width of 2.0 mm and a thickness of 10 pm had an out-of-plane deflection of 0.8 pm, an out-of-plane deflection per unit length of 1.57 x 10 ³ pm/mm, and a stress of 64 MPa. For comparison, the out-of-plane deflection of the membrane layer 100 without a perimetrical glass frit rib 120 was 168 pm and the out-of-plane deflection, per unit length was 3.31 pm/mm. Accordingly, in embodiments, a pair of perimetrical glass frit ribs 120 provide a membrane layer 100 with an out-of-plane deflection (e.g., a gravitational deflection) less than or equal to about 10.0 pm. In some embodiments, a pair of perimetrical glass frit ribs 120 provide a membrane layer 100 with an out-of-plane deflection (e.g., a gravitational deflection) less than or equal to about 5.0 pm, for example, less than or equal to about 2.5 pm. Also, in embodiments, a pair of perimetrical glass frit ribs 120 provide a membrane layer 100 with an out-of-plane deflection, per unit length, less than about 0.2 pm/mm, for example less than about 0.1 pm/mm, less than about 1.0 x 10 ² pm/mm, less than about 5.0 x 10 ³ pm/mm, less than about 2.5 x 10 ³ pm/mm or less than about 2.0 x 10 ³ pm/mm. Particularly, the out-of-plane deflection, per unit length, may be between about 0.2 pm/mm and about 0.1 pm/mm, between about 0.1 pm/mm and about 1.0 x 10 ² pm/mm, between about 1.0 x 10 ² pm/mm and about 5.0 x 10 ³ pm/mm, between about 5.0 x 10 ³ pm/mm and about 2.5 x 10 ³ pm/mm, or between about 2.5 x 10 ³ pm/mm and about 2.0 x 10 ³ pm/mm.

Example 5

[0048] Cooling of stiffened thin membranes 14 (FIG. 4) comprising a membrane layer 100 with a diameter equal to 4.0 inches (101.6 mm), an upper perimetrical glass frit rib 140 bonded to the upper surface 101, a lower perimetrical glass frit rib 140 bonded to the lower surface 103, and a 1.0 pm titanium polarizing electrode layer 110 bonded to the lower surface 103 was modeled. Each of the membrane layers 100 were formed from zirconia - 3 mole % yttria and had a thickness tm equal to 20 pm. The upper and lower perimetrical glass frit ribs 140 were offset from the perimeter 102 by 0.0 mm. The width of the upper and lower perimetrical glass frit ribs 140 ranged from 0.3 mm to 0.5 mm and the thickness of the upper and lower perimetrical glass frit ribs 140 ranged from 30 pm to 50 pm. Out-of-plane deflection and stress at the center C of the membrane layer 100 were calculated after cooling the stiffened thin membranes 10 from 900°C to 20°C. Table 5 below shows the out-of-plane deflection and stress for each of the membrane layer 100 - perimetrical glass frit rib 140 combinations.

Table 5.

Particularly, a membrane layer 100 with lower and upper perimetrical glass frit ribs 140 offset 0.0 mm from the perimeter 102 and comprising a width of 0.5 mm and a thickness of 50 pm had an out-of-plane deflection of 1.0 pm, an out-of-plane deflection per unit length of 1.97 x 10 ³ pm/mm, and a stress of 41 MPa. The membrane layer 100 with upper and lower perimetrical glass frit ribs 140 offset 0.0 mm from the perimeter 102 and comprising a width of 0.3 mm and a thickness of 30 mih had an out-of-plane deflection of 6.0 pm, an out-of-plane deflection per unit length of 1.18 x 10 ¹ pm/mm, and a stress of 7 MPa. For comparison, the out-of-plane deflection of the membrane layer 100 without a perimetrical glass frit rib 120 was 168 pm and the out-of-plane deflection, per unit length was 3.31 pm/mm. Accordingly, in embodiments, a pair of perimetrical glass frit ribs 140 provide a membrane layer 100 with an out-of-plane deflection (e.g., a gravitational deflection) less than or equal to about 10.0 pm. In some embodiments, a pair of perimetrical glass frit ribs 140 provide a membrane layer 100 with an out-of-plane deflection (e.g., a gravitational deflection) less than or equal to about 5.0 pm, for example, less than or equal to about 2.5 pm. Also, in embodiments, a pair of perimetrical glass frit ribs 140 provide a membrane layer 100 with an out-of-plane deflection, per unit length, less than about 0.2 pm/mm, for example less than about 0.1 pm/mm, less than about 1.0 x 10 ² pm/mm, less than about 5.0 x 10 ³ pm/mm, less than about 2.5 x 10 ³ pm/mm or less than about 2.0 x 10 ³ pm/mm. Particularly, the out-of-plane deflection, per unit length, may be between about 0.2 pm/mm and about 0.1 pm/mm, between about 0.1 pm/mm and about 1.0 x 10 ² pm/mm, between about 1.0 x 10 ² pm/mm and about 5.0 x 10 ³ pm/mm, between about 5.0 x 10 ³ pm/mm and about 2.5 x 10 ³ pm/mm, or between about 2.5 x 10 ³ pm/mm and about 2.0 x 10 ³ pm/mm.

[0049] In the above detailed description, numerous specific details have been set forth in order to provide a thorough understanding of embodiments described above. However, it will be clear to one skilled in the art when embodiments may be practiced without some or all of these specific details. In other instances, well-known features or processes may not be described in detail so as not to unnecessarily obscure the disclosure. Moreover, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. In case of conflict, the present specification, including the definitions herein, will control.

[0050] Although other methods and can be used in the practice or testing of the embodiments described herein, certain suitable methods and materials are described herein.

[0051] Disclosed are materials, compounds, compositions, and components that can be used for, can be used in conjunction with, can be used in preparation for, or are embodiments of the disclosed method and compositions. These and other materials are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these materials are disclosed that while specific reference of each various individual and collective combinations and permutation of these compounds may not be explicitly disclosed, each is specifically contemplated and described herein.

[0052] As used herein, the terms“upper” and“lower” refer to orientations shown in the drawings and do not refer to an exact orientations of articles or processes recited in the claims unless expressly stated otherwise. Also, the term“about” as used herein means that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and/or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art. In general, an amount, size, formulation, parameter or other quantity or characteristic is“about” or“approximate” whether or not expressly stated to be such.

[0053] The indefinite articles “a” and “an” are employed to describe elements and components of the invention. The use of these articles means that one or at least one of these elements or components is present. Although these articles are conventionally employed to signify that the modified noun is a singular noun, as used herein the articles“a” and“an” also include the plural, unless otherwise stated in specific instances. Similarly, the definite article “the”, as used herein, also signifies that the modified noun may be singular or plural, again unless otherwise stated in specific instances.

[0054] It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Thus it is intended that the specification cover the modifications and variations of the various embodiments described herein provided such modification and variations come within the scope of the appended claims and their equivalents.

Claims

1. A stiffened thin membrane:

a membrane layer comprising a ceramic composition, a thickness less than or equal to about 100 pm and a radius greater than or equal to about 20 mm and less than or equal to about 350 mm; and

a perimetrical glass frit rib bonded to a first surface of the membrane layer, the perimetrical glass frit rib comprising a thickness between about 10 pm and about 200 pm and a width of less than or equal to about 10 mm; wherein,

the perimetrical glass frit rib is spaced from a perimeter of the membrane layer by less than or equal to about 5.0 mm, and

the membrane layer with the perimetrical glass frit rib bonded to the first surface comprises an out-of-plane deflection, per unit length, less than about 0.2 pm/mm.

2. The stiffened thin membrane of claim 1, wherein the perimetrical glass frit rib has a width less than or equal to about 5.0 mm and a thickness between about 10 pm and about 100 pm.

3. The stiffened thin membrane of claim 1, wherein the out-of-plane deflection, per unit length, is less than about 0.1 pm/mm.

4. The stiffened thin membrane of claim 1, wherein the out-of-plane deflection, per unit length, is less than about 1.0 x 10 ² pm/mm.

5. The stiffened thin membrane of claim 1, wherein the perimetrical glass frit rib is spaced from the perimeter of the membrane layer by less than or equal to about 2.0 mm.

6. The stiffened thin membrane of claim 1, wherein the membrane layer is formed from at least one of zirconia, yttria stabilized zirconia, alumina, aluminium nitride, silicon carbide, magnesium alumina spinel, mullite, cordierite and fused silica, and the perimetrical glass frit rib is formed from a glass frit such that the perimetrical glass frit rib and the membrane layer have a CTE mismatch of at least 2.0 x 10 ⁶ /°C.

7. The stiffened thin membrane of claim 6, wherein the CTE mismatch between the perimetrical glass frit rib and the membrane layer is at least 4.0 x 10 ⁶ /°C.

8. The stiffened thin membrane of claim 6, wherein the CTE mismatch between the perimetrical glass frit rib and the membrane layer is between about 2.0 x 10 ⁶ /°C and about 6.0 x lO ⁶ /°C.

9. An entry window for a parallel-plate ionization chamber comprising:

a membrane layer comprising a ceramic composition, a thickness less than about or equal to about 100 pm and a radius greater than or equal to about 20 mm and less than about or equal to about 350 mm;

a perimetrical glass frit rib bonded to a first surface of the membrane layer, the perimetrical glass frit rib comprising a thickness between about 10 pm and about 200 pm and a width of less than about or equal to about 10 mm; and

a polarizing electrode layer bonded to a second surface of the membrane layer opposite the first surface, wherein,

the perimetrical glass frit rib is spaced from a perimeter of the membrane layer by less than or equal to about 5.0 mm, and

the membrane layer with the perimetrical glass frit rib bonded to the first surface comprises an out-of-plane deflection, per unit length, less than about 0.2 pm/mm.

10. The entry window for the parallel-plate ionization chamber of claim 9, wherein the polarizing electrode layer is a metal layer with a thickness less than or equal to about 10 pm.

11. The entry window for the parallel-plate ionization chamber of claim 9, wherein the perimetrical glass frit rib has a width less than or equal to about 5.0 mm and a thickness between about 10 pm and about 100 pm.

12. The entry window for the parallel-plate ionization chamber of claim 9, wherein the out-of-plane deflection, per unit length, is less than about 0.1 pm/mm.

13. The entry window for the parallel-plate ionization chamber of claim 9, wherein the out-of-plane deflection, per unit length, is less than about 1.0 x 10 ² pm/mm.

14. The entry window for the parallel-plate ionization chamber of claim 9, wherein the perimetrical glass frit rib is spaced from the perimeter of the membrane layer by less than or equal to about 2.0 mm.

15. The entry window for the parallel -plate ionization chamber of claim 9, wherein a CTE mismatch between the membrane layer and the perimetrical glass frit rib is at least 4.0 x 10 ⁶ /°C.

16. The entry window for the parallel -plate ionization chamber of claim 9, wherein a CTE mismatch between the membrane layer and the perimetrical glass frit rib is at least 6.0 x 10 ⁶ /°C.

17. A parallel-plate ionization chamber comprising:

an entry window comprising a membrane layer with a polarizing electrode and a back wall with a collecting electrode spaced apart from the entry window by a distance equal to or less than about 2.0 mm;

wherein the entry window comprises a ceramic composition, a thickness less than or equal to about 100 pm and a radius greater than or equal to about 20 mm and less than or equal to about 350 mm, and a perimetrical glass frit rib bonded to a first surface of the membrane layer, the perimetrical glass frit rib comprises a thickness between about 10 pm and about 200 pm and a width of less than or equal to about 10 mm, the polarizing electrode is bonded to a second surface of the membrane layer opposite the first surface, the perimetrical glass frit rib is spaced from a perimeter of the membrane layer by less than or equal to about 5.0 mm, and the membrane layer with the perimetrical glass frit rib bonded to the first surface comprises an out-of-plane deflection, per unit length, less than about 0.2 pm/mm.

18. The parallel-plate ionization chamber of claim 17, wherein a CTE mismatch between the membrane layer and the perimetrical glass frit rib is at least 4.0 x 10 ⁶ /°C.

19. The parallel -plate ionization chamber of claim 17, wherein the perimetrical glass frit rib has a width less than or equal to about 5.0 mm and a thickness between about 10 pm and about 100 pm.

20. The parallel -plate ionization chamber of claim 17, wherein the out-of-plane deflection, per unit length, is less than about 0.1 pm/mm.