In Late Latin there was a process of contraction whereby /i/ and /e/ in hiatus before another vowel became [j]. This glide, in turn, palatalised most preceding consonants, e.g. PALEA > *palja > paʎa ‘straw’ (It. paglia, Port. palha, Fr. paille, Sp. paja). In this paper we are concerned with words containing sequences that remained unaltered after this process had run its full course, or were incorporated into the lexicon at a later stage.
In Classical Latin vowel sequences of rising sonority as in CLIENS ‘client’, ITALIA, were always heterosyllabic.
Romanian is the one [Romance language] with the most robust diphtong/hiatus contrast. (...) Wheter a given lexical item contains a diphtong or a heterosyllabic [hiatus] séquense is generally predictiable from etymological considerations. Sequences of vocoids of rising sonority are realised as diphthongs if they come either from the breaking of lower-mid vowels, or from the palatalisation of laterals. Latin sequences in hiatus have not contracted to diphthongs in any position (ITALIA > [itáli.a] ‘Italy’, MEDIANA > [medi.ána] ‘median’). The only lexical exception known to us is [djavol] ‘devil’ from Latin DIABOLU. (...) Romanian therefore appears to be a conservative Romance language in this respect.
In French, unlike Romanian, the sequences of vocoids under discusión are quite systematically syllabified as diphthongs.
[In Spanish] the vast majority of words with etymological heterosyllabic sequences nowadays have lexical diphtongs, which is the unmarked or regular syllabification of iV sequences. [But] diphthongisation has been prevented [exceptionaly, and with dialectal variation] under the initality and stress conditions, as in [DIABOLU > di.áblo, CLIENTE > cli.énte, CREARE > cri.ár, TRIUMPHU > tri.únfo].
In Portuguese there is no diphthong/hiatus contrast. The general pattern is syllabification in hiatus, with optional gliding occurring in colloquial speech, mostly in post-tonic position, as in palác[ju] ‘palace’, glór[ja] ‘glory’. It has been noted that in this respect Portuguese is strikingly different from Spanish, French, and Italian.
We would like to suggest that this difference between Portuguese and Spanish is related to the fact that Portuguese lacks other historical sources of diphthongs. Unlike Spanish and French, mid vowels did not undergo breaking in Portuguese.
It is well known that hiatus is dispreferred cross-linguistically. Evidence for avoiding hiatus by proceses such as diphthongisation, vowel elisión, glide or consonant epéntesis, is quete overwhelming. In the case of high-nonhigh vowel sequences a very common sound change is the reclassification of heterosyllabic sequences (i.V) as tautosyllabic diphthongs (jV).
In a language like Portuguese or Catalan, for example, where there are no independent prevocalic glides from other sources to act as additional attractors, the stable articulatory structure of the diphthong may alone have an effect on hiatus sequences. In Portuguese gliding is occasionally possible in casual, colloquial speech. In this sense, the diphthong can be said to constitute a phonetically more natural structure.
Secondo toto questo, credo che en neolatino hi deveria havere una distinzione entre [j]V (ex. sapia) e [i]V (ex. història). Havemos [j] onde ja era presente en lo latino volgare, e [i] en préstetos posteriores del latino. Opzionalmente se pòte fácere un diptòngo pòs síllaba accentuata (ex. historia).