In general, the answer is no, it varies with temperature.
Finding good data can be a challenge. If you live near a well-stocked library, it becomes easier, but many of us don't, so we either rely on our technical book collections or use the web. You'll also find different data on the same materials, so it can be hard to decide what data to use, if any (part of the skew no doubt comes from composition variations normal in commercial materials). A good approach is to measure it yourself, but this can call for an unreasonable investment in time and may require equipment you don't have.
For careful work, the best strategy is probably to do a careful reading of the research literature.
When I was an ultra-high vacuum engineer, we frequently needed the physical properties of various materials as a function of temperature. The corporate library at Varian was pretty well stocked and we collected copies of reference data from other engineers. Some potential references are the books by the AVS (American Vacuum Society), the reference on thin films by Maissel and Glang, and the high vacuum book by Dushman. Alas, I've been out of that field for 30+ years and don't remember many details. Some books on solid state physics and thermodynamics can give you information to help you extrapolate from one or two data points.
