The idea to write a new book in the ?eld of ferroelectric crystals arose from some considerationsreportedinthefollowing. Inthelast5years, severalgroupsallaround the world in the ?eld of engineering and characterization of ferroelectric crystals have published more than 300 papers. The motivation for such an intense research activity is referable to the fact that the ferroelectric crystals are a key element for the most attractive and useful photonic and optoelectronic devices. In fact, during the 60ies, the scientists realized that the ferroelectric crystals could have been - ?ciently used to...