Abstract: In accordance with the present invention, there is provided a method for producing a single LTGA crystal from a polycrystalline starting material prepared from a mixture of La2O3, Ta2O5, Ga2O3, and Al2O3, wherein a mixture having a composition represented by y(La2O3)+(1?x?y?z)(Ta2O5)+z(Ga2O3)+x(Al2O3) (in the formula, 0<x?0.40/9, 3.00/9<y?3.23/9, and 5.00/9?z<5.50/9) is used as the polycrystalline starting material, and a single LTGA crystal is grown using the Z-axis as a crystal growth axis. The grown LTGA single crystal is preferably subjected to a vacuum heat treatment. The single LTGA crystal grown by the method according to the present invention, which is highly insulative and highly stable, can be utilized in such applications as a piezoelectric element of a highly reliable combustion pressure sensor useful in measurement of a combustion pressure in a combustion chamber of an internal combustion engine.

Abstract: In accordance with the present invention, there is provided a method for producing a single LTGA crystal from a polycrystalline starting material prepared from a mixture of La2O3, Ta2O5, Ga2O3, and Al2O3, wherein a mixture having a composition represented by y(La2O3)+(1-x-y-z)(Ta2O5)+z(Ga2O3)+x(Al2O3) (in the formula, 0<x?0.40/9, 3.00/9<y?3.23/9, and 5.00/9?z<5.50/9) is used as the polycrystalline starting material, and a single LTGA crystal is grown using the Z-axis as a crystal growth axis. The grown LTGA single crystal is preferably subjected to a vacuum heat treatment. The single LTGA crystal grown by the method according to the present invention, which is highly insulative and highly stable, can be utilized in such applications as a piezoelectric element of a highly reliable combustion pressure sensor useful in measurement of a combustion pressure in a combustion chamber of an internal combustion engine.

Abstract: A piezoelectric oscillator comprises a piezoelectric oscillating reed, an insulating substrate for retaining the piezoelectric oscillating reed, and a cap fixed onto the top surface of the insulating substrate for enclosing the piezoelectric oscillating reed. Four connecting electrodes are formed on the top surface of the insulating substrate for electrical connection to the oscillating reed, which are divided into two groups. Each group includes two connecting electrodes which are connected to each other by metal interconnects. The insulating substrate is rectangular, and two connecting electrodes, each of which belong to one group, are located along the shorter sides of the insulating substrate. On the bottom surface of the insulating substrate, at least two external electrodes are formed, to which metal interconnects for each group are connected through the side surface of the insulating substrate.