JPS5932438B2 - Single crystal single domainization method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for single-domaining a ferroelectric LiTa03 single crystal.

Conventionally, in order to make an X-axis pulled LiTa03 single crystal into a single stronghold, after cutting out the Z-cut, that is, the Z-plane from the created crystal by directional cutting, attaching an electrode to the cut-out Z-plane,
A voltage is applied to the electrode to create a single stronghold.

However, this method requires a Z-cut azimuth cutting process and is uneconomical as it causes a lot of loss when cutting the expensive single crystal. The present invention provides a method for economically and easily converting the X-axis pulled LlTa03 crystal into a single core by omitting the Z-cutting step. That is, the present invention provides an X-axis extension L that is created using the Czochralski method.
First, the Z-axis crystal orientation of the 1TaO3 single crystal is determined by, for example, an optical method, and as shown in FIG. 1, opposing first and second electrodes are formed on the side surface of the holding single crystal in the Z-axis direction However, a voltage is applied between the electrodes to form a single stronghold, and the Z-cutting process is omitted.

Next, an example will be described in which the method of the present invention is applied to a method for manufacturing a LiTaO3 substrate for a surface acoustic wave PIF filter for a color television receiver. A single crystal holding means, for example, a diameter of 35 mm and a length of 50 mm, for example, prepared by the Czochralski method (7) An X-axis holding LiTaO3 crystal 1 is placed under orthogonal Nicols 10 and 11 as shown in FIG. X
Rotate the axis to find the direction in which the interference draft 2 occurs.

This direction is the Z-axis direction 3. A mark indicating this Z-axis direction is placed on the bottom surface 12 of the crystal. Thereafter, as shown in FIG. 1, Pt liquid 4 is applied to one side of the X-axis lifted LiTaO3 single crystal 1 in the Z-axis direction and baked at 600° C. for 1 hour. then the first
As shown in the figure, Pd--Ag pastes 5 and 6 are applied to both sides of the single crystal holding back so as to face each other on the Z-axis, an Au wire lead wire T is attached, and baking is performed at 700 DEG C. for 1 hour. Then, a DC power source 8 is connected between the lead wires T taken out from both electrodes 5 and 6, and a DC voltage of 35 V/(m) is applied and the single crystal is heated to 700°C, which is higher than the Curie temperature (607°C).
Heat until. After that, temperature 700℃ DC voltage 35V/
After applying c7rL for 20 minutes,
The single stronghold formation is completed by slowly cooling to room temperature while voltage is applied. As a result of azimuthally cutting the Z plane of the crystal formed into a single stronghold by such a method and examining it by an etching method, it was confirmed that the entire crystal was formed into a single stronghold. As explained above, according to the method of the present invention, the pulled single crystal is directly formed into a single stronghold without cutting in the direction of the Z plane, which reduces the number of manufacturing steps and eliminates the loss of crystals due to Z cutting. , a restraining crystal can be used effectively, and Li is inexpensive.
This has an effect that greatly contributes to obtaining a TaO3 plate.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of an embodiment of the method of the present invention, and Fig. a is a front view;
Figure b is a side view, and Figure 2 is an explanation of an embodiment of the single crystal optical Z-axis detection means shown in Figure 1. 1...LiTaO3 single crystal, 2...Interference draft, 3...Z-axis direction, 4...Platinum liquid, 5,6...・Pa-Ag paste, 7...
...Lead wire, 8...Power supply, 10...
Orthogonal Nicol.

Claims (1)

[Claims] 1. When dividing the X-axis pulled LiTaO_3 single crystal into a single domain, determine the Z-axis direction of the single crystal while maintaining the pulled shape, and place the opposite first
and a method for single-domaining a single crystal, comprising forming a second electrode and applying a voltage between the electrodes to perform single-domaining.