A surface acoustic wave (SAW) substrate for a duplexer, such as a Personal Communication Service handy phone system in the U.S.A, is required to have a good temperature stability, an optimum electromechanical coupling factor, and a large reflection coefficient. The conventional method of depositing a SiO 2 film on a thick Al electrode/LiTaO 3 substrate to improve its temperature coefficient of frequency (TCF) is not effective for SAW resonator-type devices, because good frequency characteristics are not obtained due to large convex portions on the surface of SiO 2 film. However, resonators having a large reflection coefficient, an excellent TCF, and good frequency characteristics were realized using the following two new structures: (I) SiO 2 film/grooved Al electrode/LiTaO 3 structure and (II) reflection of a shear horizontal (SH) wave at free edges on a SiO 2 film/thin Al electrode/LiTaO 3 structure substrate.

No abstract

not Available.

Energy transfer in LaF3; Er, Yb is studied by observing the lifetimes of Er3+ in excited states and the excitation spectra both at room temperature and at 77 °K. It is found that the energy transfer from Er3+ (4S3/2→4I13/2) to Yb3+ (2F7/2→2F5/2) is associated with the emission of three phonons of about 350 cm−1, and that the energy transfer from Er3+ (2H9/2→4F9/2) to Yb3+ accompanied by the absorption of phonons takes place.

Here are reminiscences of some of my interactions with Marshall Stoneham and my career in industry, and particularly of his timely support for my work; and with some illustration of the importance of keeping a firm grasp on basic science to help see the wood from the trees in evaluating new technologies. It is interesting to see that fundamental theory established several decades ago needs to be further developed with some quite radical change of viewpoint when it is applied to new technology; and it is ironic that the impetus for such development of fundamental theory can be technological and commercial, rather than purely academic.M Supplementary data files are available from stacks.iop.org/JPhysCM/18/S389 Nonradiative transitionsI first met Marshall in the 1970s. I was a post-doctoral fellow looking for a problem involving impurity or defect related deep levels in semiconductors. I was fortunate to get invited to attend a small meeting of the cognoscenti in the subject at Plessey Caswell, and Marshall was one of the prominent speakers. I am quite sure you can imagine the authority and eloquence with which he spoke on many aspects of defects and related deep levels. What most caught my attention was what he had to say on nonradiative multiphonon transitions [1]. He spoke with such aplomb, nay even insouciance, on such arcane matters as nonadiabaticity, along with promoting and accepting modes, that I was both intrigued and fascinated, if not somewhat overawed.