JPS58217497A - Method for converting oxide single crystal to single domain crystal - Google Patents

Abstract

PURPOSE:To decrease the deterioration layer in the surface of a crystal in the stage of converting the multi-domain single crystal of an oxide ferrodielectric and to improve yield by sticking electrodes to said crystal by means of powder or a sintered body of the same material as the material of the single crystal and having two kinds of grain sizes and viscosities. CONSTITUTION:Arc-shaped platinum electrodes 2, 2' are provided on both side surfaces corresponding to the Z face of a crystal grown in an X-axis direction in the stage of applying a specified voltage in the Z-axis direction and converting said crystal to a single domain crystal. A mixture of powder of lithium tantalate which is the same material as the material of a single crystal of, for example, LiTaO3 which is a single crystal of ferrodielectric oxide and starch is prepd. into a paste with water and such paste is used as an electrode material in said stage. An electrode material 4 of a low viscosity kneaded with the powder of lithium tantalate and the powder of starch having fine grains is coated on both side surfaces of the single crystal 1 and the contact surfaces of the electrodes 2, 2' and an electrode material 5 of a high viscosity using lithium tantalate having coarse grain sizes is coated between the electrode materials 4 and 4. The entire part is thus formed to a uniform thickness so that an electric field is applied uniformly thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a ferroelectric oxide 11i crystal into a single domain.

So-called poling, in which a ferroelectric single crystal is made into a single domain, is well known. Various reports have been made regarding the single-domain yj method, but as a method for fixing crystals and electrodes, there are cases in which electrodes are attached to blocks cut into appropriate blocks, and methods in which electrodes are attached to blocks that have been cut into suitable blocks, and cases in which electrodes are attached to a grown crystal. There are two main types: cases in which the electrodes are attached without flowing water, and cases in which the electrodes are attached as they are.

In the former case, the crystalline part is large (Saho+, 1'(It
(If the cause is 1., in the latter case 1.!, for example, apply A (J-PCI base 1 to tongue) to the surface of platinum electrode 444. Many deteriorated layers were formed and it was necessary to cut off which part, which caused a decrease in yield.

As a method to improve the above-mentioned drawbacks, without using the base l-, the powder of +J'LQ, which is the same as the crystal to be made into a single domain, is used as a material (for example, Fl) and the electrode material and the crystal. There is a way to make it into a single C domain.

In this case, the alteration of the crystal surface is reduced, but the stability between the crystal surface and this powder is poor.
Therefore, a uniform electric field is not applied to the surface of the crystal, resulting in the formation of a partially degraded layer or the occurrence of cracks.

The present invention improves the drawbacks of the prior art described in 1 above, reduces the altered layer on the crystal surface during single domain formation, and improves the yield. There is a purpose for this purpose.

In other words, in the present invention, two types of grains with the same ltA KA as the single crystal are placed between the multi-area single crystal and the electrode, and then the grains are solidified in a state with different viscosities. In order to protect the single-domain processing, it is possible to imitate it.

For example, the L 1-1-aQ single crystal, which is a surface acoustic wave material that has recently been developed, will be explained below.
Lee.

FIG. 1 is an explanatory diagram of the case where a 1JfIIJ product grown in the X-axis direction is made into a single domain by applying a constant voltage in 7 axes and 1 direction.

The direction in which the electric field is applied is the Z direction.Arc-shaped platinum electrodes 2.2' are placed on both sides of the crystal.
jru. At this time, between the platinum electrodes 2, 2 and the crystal 1, particles of tantalate (0.1 to 50 μm) are present.
) and ivl powder are mixed and made into a paste-like form as a 4-electrode agent. In this case, the particle size may be too large or
Although the water flame is large and the 1 property is small, the thickness of the electrode material becomes small due to the irregularities on the surface of the crystal, and the altered layer 3 as shown in Fig. 2 is formed. However, in order to keep the space between the electrode and the crystal constant, the electrode material 4 is made of three layers of tantalate powder as shown in Figure 3. When arranging .5 in a smooth manner, as an electrode material of 5, (average particle size of 30
Sodium tantalate powder with a particle size of 1"-1" or more (such as powder 3071m or more) combined with water, or (1 powder of 3071m or more above) pressed into a specified shape. , using calcined melons with a kQ of 4oo'c or more, and heat them with 14!2.

The part that contacts 2- is a paste-like shale-1, which is made by mixing tantalum lithium powder of 0.1 μm or more with starch and reducing the viscosity at least lower than the above ① with water. 4- is fixed to the electrode 2.2- is used. In this way, according to the present invention, the electrode material of the tantalum alloy powder between the single crystal and the platinum electrode plate is filled evenly and in a lζ state, and moreover, the predetermined thickness is uniform throughout the entire surface. The electric field spreads uniformly over the entire crystal, making it possible to form a single domain with fewer surface-altered layers and no cracks.

Next, the present invention will be explained by examples.

Size: 5 layers grown in the X-axis direction mmφX 4 C) mm
l of LiTa0. The Z iql+ /J direction of the single crystal, which already has a polarization direction, is determined by X-rays.31 Next, as shown in Figure 1, +-1-+-a o, the /axis direction of the single crystal 1. On both sides of Ffj, add tantalate powder with fine grain size (grain size 0.1 to 1) and wood.
Ifa, mix it with water and apply a low viscosity electrode agent. For the platinum electrode 2゜2-, fine-grained rhibium tantalate powder was used in the same manner ('1 I1+).
? j'ru. .

Next, a coarse-grained (particle size of 30 μn or more) livium tantalate powder is combined with the above starch powder into 1), and a glue-like material with a higher viscosity than the fine powder described in 1-1 or a predetermined shape is prepared. 81 items of 1.4 (10°C or higher) are calcined and molded.
Form into layers. After 'ε, a certain pressure is applied between both electrodes and the electrodes are left at room temperature for a certain period of time.

This was placed in an electric furnace in the state shown in Figure 3, and 7 (10-...
Raise the temperature to 800°C. After that, 10.~1! is passed through the lead wires connected to the electrodes 2 and 2'. +V/am DC mill 4
While still hanging, it was lowered at a cooling rate of 30-40°C/'11 to obtain a single crystal of LiTa0, -6, while the same as in the above example was obtained. Using l i l'a Q, single crystal grown in the X-axis direction, -c, l
On both sides in the 'l'ill/'J direction, electrodes were formed in a single layer using powder-C of one type of particle size instead of using two types of powder as in the above embodiment. Condition C1 The same article 1'1 in the above embodiment. A single crystal of LiTaQ3 was obtained by heating at C' and applying a self-current voltage to form a medium-domain region.

゛In addition, as a result of investigating the surface altered layer of the single domain single crystal in the above two examples, as shown in Figure 2, the latter example °C
Depending on the location of the crystal, there was an altered layer 3 of 1.~2111111, and a large number of dislocations were formed in 12 dormitory. In addition, a frost-colored reaction product was deposited on the platinum electrode. However, in the method of the former embodiment of the present invention, since the surface of the single crystal electrode 4-14 is removed in 11 minutes using an electrode agent, there is less altered layer on the surface and unevenness can be eliminated. is completed lζ.

As explained above, according to the method of the present invention, it is possible to reduce the number of altered layers on the crystal surface due to the single-domain treatment, and there is no occurrence of cracks due to the single-domain treatment, resulting in the effect of improving the yield.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of one embodiment of the present invention, FIG. 2 is an explanatory diagram of the generation state of the second layer in crystal table 11 according to another embodiment, and FIG. 3 is an explanatory diagram of an embodiment of the present invention. A; +, :Juru furnace matchmaker state 3 (clear diagram. 'l: !i1 crystal, 2.2-: electricity (1'Isu, S)
;Surface alteration N. 4; Electrode agent with fine particle size! J:、1li1ine 1γantielectrode material shi・Jl、゛2゛? Procedural amendment (method) 57.12゜Method for converting oxide single crystal into single domain
Kan 1 8 -fl Tokoro Higashijo; (Miyakochiyo I
l1 Ku Maru's embryo river j "l" l sound 2 Some phase +5081
1.11°I Umbrella Co., Ltd. Noshi Furu
jllll Yo11゛ Nori Taisei Ritoji

Claims (1)

[Claims] 1. It is reasonable to use the same name for the electrode in the oxide ferroelectric Iho multi-domain single crystal to make it into a C single-domain, and the electrode material is the same as the single crystal 4A, C and 2. 6 types of particle size and viscosity are synonymous with powder or sintered body, which is characterized by strong, f, single domain power of electric oxide single crystal. 2. The above-mentioned oxide may be livium dibutyrate or (studicium tantalate).