Sumitomo Electric Industries, Limited

Yutaka Tsuji

Shigeru Nakayama

Masashi Yoshimura

Masaki Fukuma

To provide a light-transmitting window material made of a spinel sintered body, wherein the largest diameter of pores contained in the light-transmitting window material is not more than 100 &#x3bc;m, and the number of pores having a largest diameter of not less than 10 &#x3bc;m is not more than 2.0 per 1 cmof the light-transmitting window material, and wherein light scattering factors are further reduced, and a method for producing a spinel light-transmitting window material including the steps of preparing a spinel molded body; a primary sintering step of sintering the spinel molded body at normal pressure or less or in a vacuum at a temperature in the range of 1500 to 1900&#xb0; C.; and a secondary sintering step of sintering the spinel molded body under pressure at a temperature in the range of 1500 to 2000&#xb0; C., wherein the relative density of the spinel molded body after the primary sintering step is 95 to 96% and the relative density of the spinel molded body after the secondary sintering step is 99.8% or more.

Spinel light-transmitting window material and method for producing the same

A substrate having appropriate strength and allowing firm bonding to a piezoelectric substrate and the like can be obtained at a lower cost. The substrate for an SAW device is formed of spinel, and PV value representing difference in level of one main surface of the substrate is at least 2 nm and at most 8 nm. Preferably, average roughness Ra of one main surface of the substrate is at least 0.01 nm and at most 0.5 nm. With such characteristics, the main surface of the substrate to be bonded to a piezoelectric substrate of the SAW device can be bonded satisfactorily to the piezoelectric material forming the piezoelectric substrate utilizing van der Waals interaction.

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Osaka, Japan

Yutaka Tsuji