JPH0442851A - Production of lead germanate thin film - Google Patents

Abstract

PURPOSE:To directly obtain a thin film of lead germanate by the use of a simple device in a short time by using Pb-alkoxide and Ge-alkoxide as raw materials and forming a thin film of lead germanate with a spray-pyrolytic method. CONSTITUTION:A thin film of lead germanate is formed by a spray-pyrolytic method using alkoxide of lead and alkoxide of germanium as raw materials. The producing method of said thin film of lead germanate is an extremely economical one as a thin film-forming technique, capable of forming a thin film of lead germanate having pyroelectric properties by burning for a short time by the use of an industrially simple device such as a spraying device and an electric furnace. Furthermore, although an inorganic acid, an organic acid and an inorganic metallic salt, etc., is exemplified as a starting raw material in a spray pyrolytic method, highly purified metal alkoxide belonging to an organic metallic salt is readily obtained and has many excellent properties in contrast to other metallic salts such as those capable of film-forming at low temperatures.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for producing a lead germanate thin film, which is an infrared detection material.

(Prior art) In general, CdHg is a typical infrared detection material.
Semiconductors such as Te, InSb and Si and lead titanate,
There are pyroelectric materials such as lead germanate, T, S, and PVF2. The former requires cooling with liquid nitrogen, while the latter does not require cooling. Therefore, although uncooled infrared detectors using pyroelectric materials are slightly inferior in performance to cooled infrared detectors, they have features such as low cost, small size, light weight, and easy handling.
It is used in human body detectors, fire alarms, etc., and its range of use is likely to expand further in the future. Among the many pyroelectric materials, lead germanate has a relatively low melting point and is promising as a high-intensity infrared detection material.

Conventionally, thick films of lead germanate have been produced by screen printing, but there have been no examples of direct production of thin films. Therefore, until now, lead germanate thin films have been made by mixing and sintering germanium and lead oxides and polishing the resulting material. However, ceramics are generally brittle, and this method has the problem that the thickness limit is approximately 30 μm, and there are also many cracks during the processing process, making it difficult to obtain material with a large area and increasing production costs. be.

(Problems to be Solved by the Invention) In conventional methods for producing lead germanate, no suitable method for directly producing a thin film has been found.

The present invention has been made to solve the above-mentioned problems, and provides a method for producing a lead germanate thin film that can directly obtain a lead germanate thin film using a simple device and in a short time. The purpose is to provide.

(Means for Solving the Problems) In the present invention, a lead germanate thin film is manufactured by a spray pyrolysis method using lead alkoxide and germanium alkoxide as raw materials.

The procedure for producing a lead germanate thin film by the spray pyrolysis method in the present invention is as follows.

First, alkoxide and germanium alkoxide are used as starting materials, and the metal alkoxides of each component are mixed in a predetermined component ratio.Next, the mixed raw material solution is sprayed onto a heated substrate to form an amorphous pyroelectric thin film. form. Thereafter, a heat treatment is performed using an electric furnace or the like to obtain an electrically inert thin film.

(Function) As described above, in the present invention, since a solution is used as a raw material, (1) each component is mixed at the atomic level and a uniform film can be obtained. (2) Mlli composition can be easily controlled by simply adjusting the ingredient ratio of the ingredients. (3) Free pattern formation is possible by using not only flat substrates but also substrates of various shapes.

(4) There is an advantage that the film thickness can be arbitrarily set by adjusting the number of times of spraying and the concentration of the raw material solution.

In addition, from an industrial perspective, spraying is an extremely economical thin film fabrication technology that enables the formation of lead germanate thin films with pyroelectric properties in a short firing time using simple equipment such as equipment and electric furnaces. .

Furthermore, the starting materials for the spray pyrolysis method include inorganic acids, organic acids, inorganic metal salts, and organic metal salts, but among these, the metal alkoxides contained in the organic metal salts are easily obtainable with high purity. It has many advantages over other metal salts, such as the ability to form films at low temperatures.

(Embodiments of the Invention) FIG. 1 shows a flowchart of the manufacturing process of a lead germanate thin film according to the present invention, and the present invention will be described in detail below in order.

First, in the mixing step 1, the metal alkoxides of each component are mixed in a predetermined component ratio. Specifically, as the metal alkoxide, di-iso-propoxy lead (Pb(0-i-C
Jt)z) and tetra-iso-propoxygermanium (Ge(0-i-CJt)<). Note that since di-iso-propoxy lead is solid at room temperature, an ethanol solution of di-iso-propoxy lead using ethanol as a solvent is used. These solutions are weighed and mixed so that the molar ratio of pb to Ge becomes a stoichiometric composition ratio of 5-3.

Next, in a spraying step 2, the mixed solution is sprayed onto the substrate. A hand sprayer was used for spraying, and 0.0.
It is deposited on the order of 5 μm and dried in the drying step 3. These steps 2 and 3 are repeated until a predetermined film thickness is achieved.Next, in the firing step 4, the coated substrate is heated in the air at a specific temperature within the range of about 690 to 710°C using an electric furnace. Heat and bake for 10 to 30 minutes. As a result, it is possible to obtain a lead germanate thin film having a hexagonal crystal structure and having pyroelectric properties strongly oriented along the C axis of the crystal (perpendicular to the substrate surface).

It should be noted that if the firing temperature is outside the range of about 690 to 710°C, crystallization will not be possible and it is inappropriate.

Furthermore, the substrate can also be made of a heat-resistant material other than alumina.

(Effects of the Invention) As described above, according to the method for producing lead germanate of the present invention, the metal alkoxides of each component are used as starting materials and the spray pyrolysis method is adopted, so the production equipment is simple. This method has the effect of producing a lead germanate thin film in a short time.

[Brief explanation of drawings]

FIG. 3 is a flowchart for producing a lead germanate thin film according to an embodiment of the present invention. 1... Mixing process, 2... Spraying process, 3... Drying process, 4... Baking process.

Claims (1)

[Claims] (1) A method for producing a lead germanate thin film, which comprises creating a lead germanate thin film by a spray pyrolysis method using lead alkoxide and germanium alkoxide as raw materials.