W. A. Wooster
Bio: W. A. Wooster is an academic researcher. The author has contributed to research in topic(s): Quartz & Crystal twinning. The author has an hindex of 6, co-authored 6 publication(s) receiving 119 citation(s).
TL;DR: In this paper, a survey of the experimental methods used in exploring the possibilities of untwinning quartz is presented, and the effect of crystallographic orientation is discussed, and a new physical phenomenon of "piezocrescence" is defined.
Abstract: Quartz for telecommunication purposes has to be of the highest crystalline quality. A considerable proportion of raw material is rejected on account of electrical twinning. The war-time need for economy of quartz led to an investigation of means of removing this defect. The paper surveys the experimental methods used in exploring the possibilities of untwinning quartz. The basis of these methods is a heat treatment of the quartz plate while subjected to a system of stresses applied to the plate by temperature gradients, pure bending, longitudinal compression or torque. The effect of crystallographic orientation is discussed, and the new physical phenomenon of “piezocrescence” is defined.The paper also describes the practical application of the untwinning techniques to quartz-crystal plates, with particular reference to the requirements of telecommunication. It is shown that the method employing heat treatment with an applied torque may be successfully applied to many important types of quartz crystals including the BT and AT cuts. The proportion of success and the occurrence of quartz showing anomalous behaviour are discussed.
TL;DR: In this article, the authors have repeated Spezia's experiments so far as to confirm his results, but the period of months which is required for appreciable growth to occur makes the method unsuitable for industrial production.
Abstract: THE extensive use of quartz in piezoelectric oscillators has stimulated the production of synthetic quartz crystals Spezia1 in 1906 grew quartz at a temperature somewhat below 300° C from an aqueous solution containing sodium metasilicate and sodium chloride His method was to dissolve quartz in the hotter part of the container and deposit it in the cooler part We have repeated Spezia's experiments so far as to confirm his results, but the period of months which is required for appreciable growth to occur makes the method unsuitable for industrial production
TL;DR: In the Dauphine twins of quartz, the polarity of the electric axes is reversed on either side of a twin boundary as mentioned in this paper, which is known as electrical twinning and can be induced either by heating or by pressure.
Abstract: IN the Dauphine twins of quartz, the polarity of the electric axes is reversed on either side of a twin boundary. Structurally the change is slight. It has been known for some time that electrical twinning could be induced either by heating1 or by pressure2; but up to the present its elimination has not, so far as we are aware, been reported.
TL;DR: Alternative methods employing a temperature gradient, such as Spezia4 used in his pioneer experiments are re-examined, finding them to be unsatisfactory.
Abstract: DURING recent years there has been considerable interest both in Europe and the United States in the synthesis of quartz crystals large enough for use as piezo-electric oscillators in telecommunication equipment. An isothermal process for growing such crystals was described by Nora and W. A. Wooster1 in 1946 and a similar method was developed independently in Germany during the Second World War by Nacken2. The isothermal process depends on the high solubility of silica glass relative to that of α-quartz under hydrothermal conditions. In our most successful experiments we were able to deposit a total of nearly 1 mm. of good-quality quartz on to a seed crystal, cut parallel to a rhombohedral face, in an 18-hr, growth-cycle. However, difficulties were incurred in attempting to prolong the growth-cycle beyond a day, due to the devitrification of the silica glass3. We therefore re-examined alternative methods employing a temperature gradient, such as Spezia4 used in his pioneer experiments.
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TL;DR: The Cauchy-Born rule as mentioned in this paper has been widely used in the literature to relate continuum theories of elastic phenomena to typical atomic or molecular theories, and it has been used to correlate changes in positions of the entities in the latter with descriptions of deformation in the former.
Abstract: To relate continuum theories of elastic phenomena to typical atomic or molecular theories, one needs some way of correlating changes in positions of the entities in the latter with descriptions of deformation used in the former. For crystals, the most commonly used bridge used for this is the Cauchy—Born rule. In recent years, there has been a flurry of activity aimed at better understanding it and in trying to generalize it. I will describe and comment on important ideas that have been generated, point out some successes and failures of the rule and indicate kinds of applications that have motivated such work.
••15 Mar 2013