US2845542A

US2845542A - X-ray diffraction apparatus

Info

Publication number: US2845542A
Application number: US380189A
Authority: US
Inventors: Jagodzinski Heinz
Original assignee: Licentia Patent Verwaltungs GmbH
Current assignee: Licentia Patent Verwaltungs GmbH
Priority date: 1953-09-15
Filing date: 1953-09-15
Publication date: 1958-07-29
Anticipated expiration: 1975-07-29

Description

July 29, 1958 1H. JAGODZINSKI 5,

X-RAY DIFFRACTION APPARATUS Filed Sept. 15. 1953 3 Sheets-Sheet l Inventor? HEINZ. UAGoDZ/WSKL July 29, 1958 H. JAGODZINSKI X-RAY DIFFRACTION APPARATUS 3 Sheets-Sheet 2 Filed Sept. 15. 1953 I9 26 256 3/6 111; We:

Inventor? H /vz 'AsODZIIYSK July 29, 1958 H. JRGODZINSKI 2,845,542

X-RAY DIFFRACTION APPARATUS Filed Sept. 15, 1953 3 Sheets-Sheet 3 l7a 37a 35 176 376 I8 W 41a {6 r Int entan- Hsnvz TAG-0D 2m 5x! United States Patent ()fiic 2,845,542 Patented July 29, 1958 2,845,542 X-RAY DIFFRACTION APPARATUS Heinz Jagodzinski, Wurzburg, Germany, assignor to Lrcentra Patent-Verwaltungs-G. m. b. H., Hamburg, Germany The present invention relates to X-ray dilfraction apparatus 'of the type wherein a beam of monochromatic X-rays is focused upon a point on a cylindrical chamber wall which, at some location spaced from said point, carries a thin layer of a substance to be analyzed; the rays difiracted by the crystalline structure of the substance impinge upon some other portion of the cylinder wall where they may strike a photosensitive surface to produce the well-known Debye-Scherrer pattern from which the spacing of the atomic planes and other characteristics of the lattice structure of the difiracting substance can be ascertained.

It is an object of this invention to provide an improved apparatus of this description adapted to alford better utilization of the output of a single source 'of monochromatic X-rays by enabling successive high-precision analyses to be made at difierent angles of impingement yet without any modification of said output or other critical readjustments.

It is another object of this invention to provide a difiraction apparatus of the general character described above but adapted to produce two simultaneous crystallographic patterns with the aid of a single beam of monochromatic X-rays.

.It is a further object of this invention to provide, in combination with a diffraction apparatus of the character setforth, means for displacing the substance to be analyzed with respect to the X-ray beam so as to produce a crystallographic pattern representative of the mean atomic structure of said substance and free from fortuitous aberrations.

The above and other objects of theinvention will become apparent from the following description, reference beinghad to the accompanying drawing in which:

Figs. 1, 2 and 3 are diagrams illustrating the basic concepts underlying the present invention;

Fig. 4 shows a diffraction apparatus according to the invention comprising a pair of cylindrical chambers contacting in a common tangential plane along a contact line parallel with their respective axes, the figure being a section taken at right angles to the chamber axes;

Fig. 5 is a view similar to Fig. 4 but showing the apparatus rearranged to admit X-rays passing through the chambers in a .diiferent direction;

Fig. 6 is for the most part a sectional view taken on the line 6-6 of Fig. 4 but showing certain elements in elevation; and I Fig. 7 is an elevation of an insert assembly of Fig. 5.

Referring to Fig. 1, there is shown schematically at S a source of polychrome X-rays impinging upon a curved crystal 10 whose concave polished surface has a center of curvature at M, whilst the centre of the curved atom layers lies at 0. It will be noted that the point S lies on the periphery ofthe circle C, having M as center and representing the surface of the crystal, and on which there lies also the center 0 of the circle D representing the atom layers of the curved crystal. 'Ifhe'two circles forming part of the C and D osculate at P, the radius of C being one-half of that of D. As long as the source S is small, compared with the diameter of circle C, the outgoing rays reflected by the crystal will substantially all intersect ata point F, if their wavelength satisfies Braggs law. Hence the point F becomes the equivalent of a point of origin S of radiation of that wavelength. It will also be apparent that ofthe crystal 10 has appreciable axial extent, then the circles C and D may be regarded as cylinders and thesource S may be transformed from a point source into a line source parallel to the cylinder axis, whereupon the' point F will be converted into a line focus also parallel to this axis. s

Fig. 2 shows a cylindrical chamber 11a upon whose inner Well the rays of single wavelength from a monochromator 10, i. e. from a curved crystal of the character described in connection with Fig. 1, converge at F. These rays pass through a substance to be analyzed, consisting, for example, of particles in suspension and forming a thin film 12a along the inner chamber wall; some of these rays are reflected by the crystalline structure of the substance 12a and form the focussed difiraction pattern S 13a thereof along the inner periphery of the chamber 11a.

Fig. 3 shows the monochromator 10 so positioned with respect to a cylindrical chamber 11b that the focus F of the monochrome rays, while coinciding again with the inner chamber wall, will lie ahead of the film 12b comprising the substance to be analyzed; thus the rays from the virtual source F diverge as they approach the substance 12b and are partially reflected to form the focussed diffraction pattern S 13b onthe inner cylinder wall.

. From a comparison of Figs. 2 and 3 it will be apparent that the two arrangements are geometrically equivalent so far as the path ofthe rays within the chambers is concerned, so that in either case the focus F may be regarded as a virtual source of monochromatic rays. This relationship is utilized, in accordance with an important feature of the present invention, for the double exploitation of the beam of X-rays from a single monochromator by combining two cylindrical chambers, such as those shown schematically in Figs. 2 and 3, into a single structure as illustrated in the subsequent figures. Thefirst chamber 11a exploits all reflections with Braggangles smaller than the second chamber 11b those with angles larger than 90.

Figs. 46 show the two

chambers

11a, 11b located side by side in a housing 20 and merging with each'other so that their inner cylindrical surfaces contact in a common tangential plane along a contact line parallel with their respective axes, the monochromator .10 being so located. outside these chambers that the focus F of its outgoing rays will coincide with this contact line. The latter is the location for a slot 14 in the wall separating the chambers and by corresponding slots in a pair of

X-ray films

15a, 15b lining a major portion of the

chambers

11a, 11b, respectively. These rings are held in place by upper and

lower clamping rings

16a, 17a and 16b, 17b fitting tightly but removably inside the respective chambers.

The housing 20 rests on a base plate 18, which closes the lower end of

chambers

11a, 11b, and also has a platform 19 supporting a motor 21 for a purpose presently to be described. It is further formed on its outside with a central recess 22 extending horizontally all around the housing and merging almost tangentially, at three points, with each of the

chambers

11a, 11b, thereby forming three

windows

23a, 24a, 25a in chamber 11a and three similar windows 23b, 24b, 25b in chamber 11b. The windows of each chamber define three corners. of a 3 square whose fourth corner is represented by the slot 14; thus, corresponding windows such as 23a, 23b form a pair facing each other across this slot.

Positioned externally of each window 23a25a and 23b-25b so as to bridge the recess 22 is a

respective diaphragm plate

27a, 28a and 27b, 28b having its aperture oriented toward the slot 14. The space within the recess 22 between these diaphragm plates and the housing 20 defines a channel for a

respective carriage

29a, 30a, 31a and 29b, 30b, 31b adapted to hold the specimens to be analyzed by the apparatus of the invention whilst the other openings, through which the X-rays do not emerge, are covered with exchangeable blind plates 26. Each of these carriages 29-31 has a pyramidal aperture adapted to be spanned by a specimen-supporting frame, the latter comprising, for example, a pair of foils, glass plates or the like holding the specimen in suspension between them. The carriages 29a-31a and 29b-31b are reciprocated in unison past their respective windows 23a-25a and 23b-25b by a mechanism comprising a wire 32 which passes around idler rollers 33 in recess 22 and interconnects the carriages with one another, the wire being also secured to a dog 34 on the shaft of motor 21. In view of this reciprocation, the apertures of the carriages extend beyond those of the corresponding diaphragm members 27a28a and 27b-28b in the horizontal plane.

The reciprocating mechanism just described serves the purpose of freeing the diffraction patterns of the specimens from irregularities due to local structural flaws. The thickness of the specimens should not exceed 0.1 mm. and they should be accurately guided within recess 22 with a transverse play of preferably not more than 0.02 mm. in the horizontal plane, i. e. in radial direction of the chambers.

The housing 20 is rotatable, with respect to the fixed source of radiation represented by the monochromator 10, about a shaft 35 extending downwardly from the base plate 18; the

chambers

11a and 11b thus can occupy any of three operative positions relative to the source 10 spaced apart by 45 angles. In a first of these positions, shown in Figs. 4 and 6, the rays pass from source 10 through window 24a and slot 14 toward window 24b; in a second position, illustrated in Fig. 5, the rays from source 10 traverse window 25a and slot 14 to reach Window 25b; and in a third position, not shown but symmetrically identical with that of Fig. 5, the rays enter through window 23a and continue through slot 14 toward window 23b.

A pair of inserts 36a, 36b serve as a means for shielding the

films

15a, 15b against stray radiation due to diffraction in air and also subdivides the

chambers

11a, 11b into a plurality of compartments within which separate diffraction patterns from different specimens may be projected simultaneously upon different portions of the films. These inserts comprise bottom plates 37a, 37b, upstanding shield members 38a, 38b forming channels directed toward the aperture 14, and

horizontal disks

39a, 40a and 39b, 40b adapted to serve as partition means between the several compartments. The inserts 36a, 36b, which can be detachably secured to the base plate 18, are designed for the operative position of Figs. 4 and 6 and are replaced by diiferent inserts 41a, 41b, Figs. and 7, when the apparatus is rotated into the position of Fig. 5 or into the third operative position analogous thereto. The latter inserts, as illustrated particularly for the insert 41a in Fig. 7, comprise bottom and

top plates

42 and 43, an upstanding shield member 44 and partitioning disks 45, 46. The

plates

42, 43 and the disks 45, 46 may be segmental rather than circular, as seen in Fig. 5, to facilitate insertion and removal. It will be understood that the inserts 41a, 41b may be inverted and placed on their top plates 43 in order to serve for the proper guidance of the rays in the third operative position of the apparatus.

The incoming and diffracted X-rays have been illustrated in dot-dash lines in Figs. 4, 5 and 6, with the primary rays distinguished by longer dashes from the secondary or diffracted ones. It will be appreciated that the

films

15a, 15b, as shown in the drawing, are to be suitably apertured adjacent the slot 14 and also the entrance and exit points of the primary ray where the specimens to be analyzed are located, this being at the windows 24a, 24b in Fig. 4 and at the

windows

25a, 25b in Fig. 5. The momentarily unused windows are always covered by the film, as illustrated, in order to provide the widest possible diffraction pattern.

If a narrow-beam tube is used as the source of X-rays directed upon the monochromator 10, and if the aboveindicated tolerances are observed, then the system according to the present invention will produce patterns of high luminous intensity and great sharpness of definition, coupled with considerable resolving power and very little blurring, so that even very faint lines adjacent lines of great intensity can still be recognized. With a chamber diameter of 114.6 mm., Cu-K natural radiation and observation of the tolerances referred to, using a suitable monochromator, the following values have been obtained by way of example:

Resolving power: Lattice plane spacings of the order of 10- Angstrom can be ascertained with sharp focusing.

Grating constant: Accurate to 05x10" Angstrom.

Determination of particle sizes from line width (according to M. v. Laue): up to 50,000 Angstrom.

Since the diifracted rays will impinge rather obliquely upon portions of the X-ray films at 250 and 25b, it is advisable to provide these films with emulsion on one side only.

The invention is, of course, not limited to the specific embodiment described and illustrated, many modifications and adaptations being possible within the scope of the appended claims.

Iclaim:

1. In an X-ray ditfraction apparatus, in combination, a pair of cylindrical chambers positioned alongside each other and having inner surfaces contacting each other along a contact line parallel with their respective axes, and a source of monochromatic X-rays focused upon said contact line.

2. An X-ray difiraction apparatus comprising a pair of cylindrical chambers positioned alongside each other and having inner surfaces contacting each other along a contact line parallel with their respective axes at the inner surfaces thereof, said chambers having walls provided with an aperture at said contact line and with a pair of openings aligned with said aperture and positioned on opposite sides thereof, supporting means at each of said openings adapted to support specimens to be analyzed in a position substantially flush with the inner surface of said chamber walls, a source of monochromatic X-rays focused upon said contact line, said X-rays passing through both of said chambers by way of said openings and said aperture, and X-ray-sensitive film means along said inner surface in the path of rays substantially simultaneously diffracted by said specimens.

3. An X-ray diffraction apparatus comprising a pair of cylindrical chambers of like diameter positioned alongside each other and having inner surfaces contacting each other along a contact line parallel with their respective axes at the inner surfaces thereof, said chambers having walls provided with an aperture at said contact line and with a pair of openings aligned with said aperture and positioned on opposite sides thereof, supporting means at each of said openings adapted to hold specimens substantially not exceeding 0.1 mm. in thickness and to support said specimens in a position substantially flush with the inner surface of said chamber walls, a source of monochromatic X-rays focused upon said contact line, said X-rays passing through both of said chamhas by way of said openings and said aperture, and X- ray-sensitive film means along said inner surface in the path of rays substantially simultaneously diffracted by said specimens.

4. An X-ray diffraction apparatus comprising a monochromator emitting a single-wavelength beam of X-rays, a pair of cylindrical chambers alongside each other and in contact with each other along a narrow area, said chambers having walls provided with an aperture at said narrow area and with a plurality of pairs of openings aligned with and positioned on opposite sides of said aperture, said chambers being simultaneously displaceable with respectto said monochromator for selectively aligning any of said pair of openings with said monochromator, thereby admitting said beam into both of-said chambers by way of one of said aligned pair of openings and said aperture, supporting means at all of said openings adapted to hold specimens to be analyzed substantially flush with the inner surface of said walls in the path of said beam, and X-ray-sensitive film means along said inner surface in the path of rays diffracted by said specimens.

5. An X-ray diffraction apparatus comprising a cylindrical diffraction chamber, a monochromator emitting a single-Wavelength beam of X-rays focused upon a line parallel with the axis and located in the inner surface of said cylindrical chamber, pivot means at said line enabling said chamber to be rotated about said line with respect to said monochromator, said chamber having a Wall provided with a plurality of openings adapted to admit said beam into said chamber in different rotary positions of said chamber, supporting means for holding a specimen to be analyzed at an opening aligned with said beam and in a position substantially flush with the inner surface of said wall, and X-ray-sensitive film means along said inner surface in the path of rays diffracted by said specimen.

6. An X-ray diffraction apparatus comprising a cylindrical diffraction chamber, a monochromator emitting a single-wavelength beam of X-rays having a line focus coinciding with a line parallel with the axis and located in the inner surface of said cylindrical chamber, pivot means at said line enabling said chamber to be rotated about said line with respect to said monochromator, said chamber having a Wall provided With a plurality of openings adapted to admit said beam into said chamber in different rotary positions of said chamber, at least one transverse disk opaque to said X-rays and subdividing said chamber into a plurality of cylindrical compartments each adapted to receivepart of said beam, sup porting means for holding respective specimens to be analyzed at an opening aligned with said beam and sub stantially flush with the inner surface of said wall in each of said compartments, and X-ray-sensitive film means along said inner surface in each of said compartments positioned in the path of rays diffracted by said respective specimens.

7. An X-ray diffraction apparatus comprising a cylindrical diffraction chamber, a monochromator emitting a single-wavelength beam of X-rays focused upon a line parallel With the axis and located in the inner surface of said cylindrical chamber, said chamber having a wall provided With at least one opening for admitting said beam into said chamber, movable supporting means at said opening for holding a specimen to be analyzed, of a thickness substantially not exceeding 0.1 mm., in the path of said beam and substantially flush with the inner surface of said Wall, mechanism for reciprocating said supporting means within the limits of said opening, said mechanism including guide means adapted to guide said specimen along said cylindrical inner surface with a radial play of not more than substantially 0.02 mm., and X-ray-sensitive film means along said inner surface positioned in the path of rays diffracted 'by said specimen.

8. An X-ray diffraction apparatus comprising a pair of cylindrical diffraction chambers merging at a line parallel with the axes and located 111 the inner surfaces of both said cylindrical chambers, respectively, a monochromator emitting a single-wavelengthbeam of X-rays focused upon said line, pivot means atsaid line enabling said chambers to be simultaneously rotated about said line with respect to said monochromator, said chambers having walls provided with an aperture at said line and with a plurality of pairs of openings aligned with and positioned on opposite sides of said aperture, different pairs of openings being aligned With said beam in different rotary positions of said chambers, supporting means for holding specimens to be analyzed at a pair of openings aligned with said beam and in a position substantially flush with the inner surface of said walls, and X-ray-sensitive film means along said inner surface in the path of rays diffracted by said specimens.

9. An X-ray diffraction apparatus comprising a pair of cylindrical diffraction chambers merging at a line parallel with the axes and located in the inner surfaces of both saidv cylindrical chambers, respectively, a monochromator emitting a single-wavelength beam of X-rays focused on said line, said chambers having walls provided with an aperture at said line and with a plurality of pairs of openings aligned with and positioned on opposite sides of said aperture, said beam entering said chambers by way of one of said openings and said aperture, shield means flanking said aperture and having aligned elongated openings on opposite sides of said aperture,

, said elongated openings also being aligned with one of having a line focus coinciding with said line, said chambers said pairs of openings to ward off stray rays, supporting means for holding specimens to be analyzed at said openings in a position substantially flushwith the inner surface of said walls, and X-ray-sensitive film means along said inner surface in the path of rays diffracted by said specimens.

, 10. An X-ray diffraction apparatus comprising a pair of cylindrical diffraction chambers merging at a line parallel with the axes and located in the inner surfaces of both said cylindrical chambers, respectively, a monochromator emitting a single-wavelength beam of X-rays having walls provided with an aperture at said line and with at least two openings aligned with and positioned on opposite sides of said aperture, said beam entering said chambers by way of certain of said openings and said aperture, at least one transverse disk opaque to said X-rays in each of said chambers and subdividing same into a plurality of cylindrical compartments 'each adapted to receive part of said beam, supporting means for holding respective specimens to be analyzed at all of said openings in a position substantially flush with the inner surface of said walls in each of said compartments, and X-ray-sensitive film means along said inner surface in each of said compartments positioned in the path of rays diffracted by said respective specimens.

11. An X-ray diffraction apparatus comprising a shaft, a structure rotatable around said shaft comprising a pair of cylindrical chambers of like diameter meeting at a line parallel with the axes and located in the inner surfaces of both of said cylindrical chambers, respectively, and coinciding with the axis of said shaft said structure having a slit at said line, said chambers communicating with each other by way of said slit, a monochromator emitting a single-wavelength beam of X-rays having a line focus coinciding with said axis, said chambers having walls provided with a plurality of pairs of openings aligned with and positioned on opposite sides of said slit, thereby admitting said beam into both of said chambers in each of a plurality of rotary positions of said structure, shield means flanking said slit to ward off stray rays, at least one transverse disk opaque to said X-rays in each of said chambers and subdividing same into a plurality of cylindrical compartments each adapted to receive part of said beam, supporting means for holding respective specimens to be.-

analyzed at openings aligned with said beam in a position substantially flush with the inner surface of said walls in each of said compartments, and X-ray-sensitive film means along said inner surface in each of said compartments positioned in the path of rays diffracted by said respective specimens.

12. An X-ray diffraction apparatus comprising a pair of cylindrical diffraction chambers meeting at a line parallel with the axes and located in the inner surfaces of both said cylindrical chambers, respectively, a monochromator emitting a single-wavelength beam of X-rays focused upon said line, said chambers having walls provided with an aperture at said line and with a pair of openings aligned with and positioned in said walls on opposite sides of said aperture, said beam entering said chambers by way of one of said openings and passing said aperture, movable supporting means at each of said openings for holding specimens to be analyzed in the path of said beam, mechanism for reciprocating said supporting means within the limits of said openings, and Xray-sensitive film means in said chambers positioned in the path of rays diffracted by said specimens.

13. An X-ray diffraction apparatus comprising a pair of cylindrical diffraction chambers meeting at a line parallel with the axes and located in the inner surfaces 1.":

of both said cylindrical chambers, respectively, a monochromator emitting a single-wavelength beam of X-rays focused upon said line, said chambers having walls provided with an aperture at said line and with a plurality of pairs of openings aligned with and positioned on opposite sides of said aperture, a supporting structure for said chambers having pivot means in alignment with said line and adapted to rotate different ones of said pairs of openings into alignment with said beam, thereby admitting said beam into both of said chambers simultaneously, a movable carriage at each of said openings for holding specimens to be analyzed in the path of said beam, mechanism on said supporting structure for reciprocating all of said carriages within the limits of said openings, said mechanism comprising a motor, a dog entrained by said motor and link means connecting said dog with all of said carriages, and X-raysensitive film means in said chambers positioned in the path of rays diffracted by said specimens.

14. In an X-ray diffraction apparatus including a narrow-beam X-ray tube, in combination, a curved focusing monochromator in the path of an X-ray beam emitted from said tube for transmitting a focused monochromatic beam; a body formed with two cylindrical cavities of equal diameter constituting two diffraction chambers,

the inner surfaces of said cylindrical cavities contacting each other along a contact line parallel with their respective axes, said contact line being located in the focal line of said X-ray beam focused by said monochromator;

positioning means for positioning a first substance at a portion of the inner surface of one of said chambers opposite said contact line and in the path of said focused X-ray beam so that the diffraction of said focused X-ray beam after passing through said first substance can be recorded in said one chamber; and means for simultaneously positioning a second substance at a portion of the inner surface of the other of said chambers opposite said contact line and in the path of said focused X-ray F beam, so that the back reflection of said focused X-ray H common aperture and for leaving the other chamber through the second aperture thereof; and wherein said positioning means comprise supporting means adjacent to said second apertures, respectively, adapted to hold specimens of said substances in alignment with said portions, respectively, of said inner surfaces; and wherein X-ray responsive means are positioned within said chambers along said walls in the path of rays diffracted by said respective specimens.

16. An X-ray apparatus as set forth in claim 15, wherein said X-ray responsive means are X-ray sensitive film means.

17. An X-ray apparatus as set forth in claim 16, wherein one of said X-ray sensitive film means is mounted in the path of the diffracted X-rays passing through one of said specimens held by one of said supporting means at said second aperture of said one of said chambers, while another of said X-ray sensitive means is mounted in the path of the diffracted X-rays reflected by the other one of said specimens held by another one of said supporting means at said second aperture of said other one of said chambers.

References Cited in the file of this patent UNITED STATES PATENTS 2,317,329 McLachlan Apr. 20, 1943 2,347,638 McLachlan Apr. 25, 1944 2,617,942 McLachlan et a1 Nov. 11, 1952 2,645,720 Gross July 14, 1953 OTHER REFERENCES Focusing X-ray Monochromators, C. S. Smith, Review of Scientific Instruments, June 1941, pages 312-314.