Zero temperature coefficient of resonant frequency in LiTaO3length expander bars

Zero temperature coefficient of resonant frequency has been found in LiTaO
3
length expander bars with orientations zyw (+ 30 deg), zyw (+35 deg), and zyw (+45 deg). These bars have large coupling constants k
32
(more than 20 percent). The zyw (+30 deg) bar is the most promising for wide-band bandpass filter applications because it shows the smallest change in the coupling constants at ordinary temperatures.